Glossary of computer terms

We are passionate about to make computers easy for the older adult community. Most people get overwhelmed with all the "jargon" that is associated with computers or other technology, so we try to explain as many things as we can in plain English.
For reference, we provide a glossary on this page to explain what different technical terms mean. If you ever see something on our website that you don't understand, please let us know. We want to explain our technology and services in a way that everyone can understand. Feel free to drop us a note.

Antivirus program

An Antivirus program is a program that protects your computer from viruses. It protects your computer by examining all files that are downloaded from the Internet, files the come through email, and will perform regular scans of your computer to ensure it is virus free. Since new viruses are created every day, it is important that Antivirus programs are set up to automatically download the latest virus information on a daily basis.


An application, or application program, is a software program that runs on your computer. Web browsers, e-mail programs, word processors, games, and utilities are all applications. The word "application" is used because each program has a specific application for the user.

For example, a word processor can help a student create a research paper, while a video game can prevent the student from getting the paper done. Definition from the Tech Terms Computer Dictionary.


A byte is a set of 8 bits that represent a single character in the computer's memory. Do not confuse this term with "bite" as in taking a bite of a cookie, because that is totally different. While bits are often used to measure data transfer speeds, bytes are used to measure file sizes, hard disk space, and computer memory. Larger amounts of data are measured in units such as megabytes, gigabytes, and terabytes.

For example, one kilobyte is equal to 1,024 bytes. Definition from the Tech Terms Computer Dictionary.

CD Stands for "Compact Disc"

CDs are circular discs that are 4.75 in (12 cm) in diameter. The CD standard was proposed by Sony and Philips in 1980 and the technology was introduced to the U.S. market in 1983. CDs can hold up to 700 MB of data or 80 minutes of audio. The data on a CD is stored as small notches on the disc and is read by a laser from an optical drive.

The drives translate the notches (which represent 1's and 0's) into usable data. The first CDs were audio CDs, which eventually replaced audio tapes (which earlier replaced records).

Audio CDs have the advantage of allowing the user to jump to different places on the disc. CDs can also be listened to an unlimited number of times without losing quality. Audio tapes can start to lose quality after listening to them as few as ten times. This is because the laser that reads the data on a CD doesn't put pressure on the disc, whereas the playheads on a tape deck slowly wear away the magnetic strip on the tape.

In 1985, CD-ROMs hit the computer market. Because they could store far more information than floppy discs (700 MB compared to 1.4 MB), CDs soon became the most common software format. In 1988, the CD-R (CD-Recordable) technology was introduced, allowing computer users to burn their own CDs. However, this technology did not become mainstream until the late 1990s. A smaller 3" CD, called "CD-3" is also available and is readable by most tray-loading CD-ROM drives. Definition from the Tech Terms Computer Dictionary.

Compact Flash (CF)

Often abbreviated as simply "CF" Compact Flash is a type of flash memory. Compact flash cards are most commonly used for storing pictures in digital cameras, but are also used in devices such as PDAs and portable music players. There are two types of Compact Flash cards, creatively named "Type I" and "Type II"

Type I cards are 3.3 mm thick, while Type II are 5 mm thick. IBM makes a "MicroDrive" card that has the same dimensions as a Type II CF card, but uses an actual hard drive construction rather than flash memory. Compact Flash cards originally could only store a few megabyes of data, but now can store several gigabytes.

The new CF+ standard can store a possible 137 GB of data. I don't know about you, but I'd think about backing up that information before throwing the card in my pocket. Definition from the Tech Terms Computer Dictionary.

Defragment Defragmenting

Your hard disk is a great way to boost the performance of your computer. Though the term "defragment" sounds a little abrasive, it is actually a simple and helpful process. After all, a defragmented hard disk is a happy hard disk. Adding and deleting files from your hard disk is a common task. Unfortunately, this process is not always done very efficiently.

For example, when you delete a bunch of little files and add a new large file, the file may get broken up into mulitple sections on the hard disk. The computer will still read the newly added file as a single valid file, but the drive will have to scan multiple parts of the disk to read it. Because hard disk seek time is one of the most significant bottlenecks in a computer's performance, this can drag down your computer's speed quite a bit.

If you have a ton of "fragmented" files on your hard disk, you might hear extra grinding, sputtering, and other weird noises coming from your computer. You computer does not like having fragmented files any more than you do. This is why defragmenting your hard disk is such a good idea. When you start to hear extra grinding sounds, or your computer doesn't open files as quickly as it did before, it's time to defragment.

With Windows, you can use the pre-installed Intel defragment program to defragment your hard disk. You can also use a commercial software program like Norton Utilities to defragment your hard disk more efficiently and with more options.

For Mac users, a disk utility such as DiskWarrior or Tech Tool Pro is the only way to do it. If you use your computer daily, defragmenting your hard drive once a month should keep the fragment-fiends away. Definition from the Tech Terms Computer Dictionary.


Your computer's desktop is much like a physical desktop. You probably keep a number of commonly used items on your desk such as pens, papers, folders, and other items. Your computer's desktop serves the same purpose to give you easy access to items on your hard drive. It is common to store frequently used files, folders, and programs on your desktop. This allows you to access the items quickly instead of digging through the directories on your hard drive each time you want to open them.

Both the Macintosh and Windows interfaces use the desktop as a central part of the interface. Both operating systems allow you to move items on and off the desktop as you wish and offer organization tools to arrange and clean up the items on the desktop. Yes, it would be nice if there was an option like that for a real-life desktop. You can also customize your computer's desktop with the pattern or background image of your choice. Definition from the Tech Terms Computer Dictionary.

DVD Stands for "Digital Versatile Disc"

It can also stand for "Digital Video Disc" but with the mulitple uses of DVDs, the term "Digital Versatile Disc" is more correct. Yep, the technology naming people just love to confuse us. A DVD is a high-capacity optical disc that looks like a CD, but can store much more information.

While a CD can store 650 to 700 MB of data, a single-layer, single-sided DVD can store 4.7 GB of data. This enables massive computer applications and full-length movies to be stored on a single DVD. The advanced DVD formats are even more amazing. There is a two-layer standard that doubles the single-sided capacity to 8.5 GB. These disks can also be double-sided, ramping up the maximum storage on a single disc to 17 GB.

That's 26 times more data than a CD can hold! To be able to read DVDs in your computer you'll need a DVD-ROM drive. Fortunately, DVD players can also read CDs. To play DVD movies on your computer, you'll need to have a graphics card with a DVD-decoder, which most computers now have. Definition from the Tech Terms Computer Dictionary.


Just to be clear, the first syllable is pronounced "eath" as in "Heath Bar" not like "eth" as in Bethany. Some people find this out the hard way (ridiculing laughter), but at least you don't have to. Ethernet is the most common type of connection computers use in a local area network (LAN).

An Ethernet port looks much like a regular phone jack, but it is slightly wider. This port can be used to connect your computer to another computer, a local network, or an external DSL or cable modem. Two widely-used forms of Ethernet are 10BaseT and 100BaseT. In a 10BaseT Ethernet connection, data transfer speeds can reach 10 mbps (megabits per second) through a copper cable. In a 100BaseT Ethernet connection, transfer speeds can get up to 100 mbps.

There is also a new technology called "Gigabit" Ethernet, where data transfer rates peak at 1000 mbps. Now that's fast. Definition from the Tech Terms Computer Dictionary.


A file is a collection of data stored in one unit, identified by a filename. It can be a document, picture, audio or video stream, data library, application, or other collection of data. The following is a brief description of each file type. Documents include text files, such as a Word documents, RTF (Rich Text Format) documents, PDFs, Web pages, and others. Pictures include JPEGs, GIFs, BMPs, and layered image files, such as Photoshop documents (PSDs).

Audio files include MP3s, AACs, WAVs, AIFs, and several others. Video files can be encoded in MPEG, MOV, WMV, or DV formats, just to name a few. A library file is a unit of data that is referenced by a specific program or the operating system itself. These include plug-ins, components, scripts, and many others. An application is a program, or executable file. Programs such as Microsoft Internet Explorer and Apple iTunes are both applications, but are also files.

Files can be opened, saved, deleted, and moved to different folders. They can also be transferred across network connections or downloaded from the Internet. A file's type can be determined by viewing the file's icon or by reading the file extension. If the file type is associated with a specific application, double-clicking the file will typically open the file within the program. Definition from the Tech Terms Computer Dictionary.


Popular web browser that many people use as an alternative to Internet Explorer.

Flash Drive

Flash drives have many names — jump drives, thumb drives, pen drives, and USB keychain drives. Regardless of what you call them, they all refer to the same thing, which is a small data storage device that uses flash memory and has a built-in USB connection. Flash drives are typically no more than two to three inches in length and less than an inch in width. Their size and shape may resemble a thumb or a small pen (which is where the names "thumb drive" and "pen drive" come from).

Flash drives are also very thin, often having a depth of less than a centimeter. Because of their small form factor, they are highly portable and can easily fit in a pocket or on a keychain (hence the name "keychain drive"). Early flash drives could store only a few megabytes of data, but modern flash drives can store several gigabytes of information.

Since they are small in size but have large storage capacities, flash drives have replaced most previous portable data storage mediums such as floppy disks and removable hard disks like Zip disks. Because they have a built-in USB connection, flash drives also don't require a special disk drive to be used. Instead, they can be used on any computer with a USB port, which nearly all modern computers have. Definition from the Tech Terms Computer Dictionary.

Flash Memory

Flash memory is a type of electrically erasable programmable read-only memory (EEPROM). Whew, that's a mouthful. The name comes from how the memory is designed -- a section of memory cells can be erased in a single action or in a "flash". A common use of flash memory is to store the BIOS settings in a computer's ROM. When the BIOS needs to be changed, the flash memory can be written in blocks, rather than bytes, making it easy to update. Most modems use flash memory for the same reason.

Though flash memory was originally used inside computers, it has invaded many other areas outside the box. Flash memory cards used for digital cameras, cellular phones, networking hardware, and PC cards. Though the memory's read/write speed is not lightning fast, it is nice to be able to tote around a little card rather than a cumbersome hard drive. Definition from the Tech Terms Computer Dictionary.

Gigabyte (GB)

A gigabyte is 2 to the 30th power, or 1,073,741,824 bytes. It can be estimated as 10 to the 9th power, or one billion (1,000,000,000) bytes. A gigabyte is 1,024 megabytes and precedes the terabyte unit of measurement. Hard drive sizes are typically measured in gigabytes, such as a 160GB or 250GB drive. The term gigabyte is often often abbreviated as simply a "gig" in speech. For example, if you have a 250GB hard drive, you could say, "I have 250 gigs of disk space." The prefix "giga" comes from the Greek word "gigas" meaning giant. Definition from the Tech Terms Computer Dictionary.

Hard Drive

The hard drive is what stores all your data. It houses the hard disk, where all your files and folders are physically located. A typical hard drive is only slightly larger than your hand, yet can hold over 100 GB of data. The data is stored on a stack of disks that are mounted inside a solid encasement. These disks spin extremely fast (typically at either 5400 or 7200 RPM) so that data can be accessed immediately from anywhere on the drive.

The data is stored on the hard drive magnetically, so it stays on the drive even after the power supply is turned off. The term "hard drive" is actually short for "hard disk drive" The term "hard disk" refers to the actual disks inside the drive. However, all three of these terms are usually seen as referring to the same thing the place where your data is stored. Since I use the term "hard drive" most often, that is the correct one to use. Definition from the Tech Terms Computer Dictionary.


A hotlink, also called a hyperlink, is a section of text or a graphic that will open another application or webpage when you click on it. Instant Message (IM) Instant messaging, or "IMing" as frequent users call it, has become a popular way to communicate over the Internet. Two people with the same IM client software can type messages back in forth in a private online chat session. IM software allows users to build a list of friends, or "buddies" and displays what other users are online.

After seeing who is online, the user can open up chat sessions with as many other people as he or she wants. While I find it difficult to focus on one conversation at a time, apparently some teenage girls that can keep more than ten conversations going at once. Instant messaging can be a much more efficient way to communicate with others than sending multiple e-mails back and forth. For this reason, IMing has become a useful tool among friends and co-workers. Some people even find it more convenient to IM their friends than to talk on the phone, which I do not understand. Definition from the Tech Terms Computer Dictionary.


Believe it or not, the Internet was created way back in 1969, during the Cold War, by the United States military. It was meant to be a "nuke-proof" communications network. Today, the Internet spreads across the globe and consists of countless networks and computers, allowing millions of people to share information.

Data that travels long distances on the Internet is transferred on huge lines known collectively as the Internet backbone. The Internet is now maintained by the major Internet service providers such as MCI Worldcom, Sprint, GTE, ANS, and UUNET. Because these providers make huge amounts of revenue off the Internet, they are motivated to maintain consistent and fast connections which benefits everyday Internet users like you and me.

Many people think the Internet and the World Wide Web are the same thing. They're not! The World Wide Web is what you are browsing right now. It is one of the many features of the Internet. E-mail, FTP, and Instant Messaging are also features of the Internet. Definition from the Tech Terms Computer Dictionary.

Internet Explorer (IE)

Internet Explorer is the standard Web Browser that comes with Microsoft Windows. Internet Service Provider (ISP) In order to connect to the Internet, you need an ISP. It is the company that you pay a monthly fee to in order to use the Internet. If you use a dial-up modem to connect to your ISP, a point-to-point protocol (PPP) connection is established with another modem on the ISP's end.

That modem connects to one of the ISP's routers, which routes you to the Internet "backbone" From there, you can access information from anywhere around the world. DSL and cable modems work the same way, except after you connect the first time, you are always connected. Definition from the Tech Terms Computer Dictionary.

Kilobytes (KB)

A kilobyte is 2 to the 10th power, or 1,024 bytes. "But doesn't 'kilo' means one thousand?" you ask. Well yes, but in the computer world, certain rules and guidelines don't have the same influence they do in other areas of life. Just ask any computer programmer.

A kilobyte is technically 1,024 bytes because it is measured by 2^10, which equals 1,024. However, kilobytes are often estimated as 10 to the 3rd power, or 1,000 bytes. While this makes it easier to add kilobytes together, estimating can throw off larger measurements. This is because 1,024 kilobytes equal one megabyte, 1,024 megabytes equal one gigabyte, and so on.

Most small files on your computer are measured in kilobytes. For example, thumbnail images might use only 5 to 10KB of space. A larger 900x600 pixel JPEG image can take up 250KB of space. Text files are often less than 1KB. Most documents you save on your computer should be between 1 and 1,024KB. Anything larger than 1,024KB is measured in megabytes. Definition from the Tech Terms Computer Dictionary.


Laptop computers, also known as notebooks, are portable computers that you can take with you and use in different environments. They include a screen, keyboard, and a trackpad or trackball, which serves as the mouse. Because laptops are meant to be used on the go, they have a battery which allows them to operate without being plugged into a power outlet. Laptops also include a power adapter that allows them to use power from an outlet and recharges the battery.

While portable computers used to be significantly slower and less capable than desktop computers, advances in manufacturing technology have enabled laptops to perform nearly as well as their desktop counterparts. In fact, high-end laptops often perform better than low or even mid-range desktop systems. Most laptops also include several I/O ports, such as USB ports, that allow standard keyboards and mice to be used with the laptop.

Modern laptops often include a wireless networking adapter as well, allowing users to access the Internet without requiring any wires. While laptops can be powerful and convenient, the convenience often comes at a price. Most laptops cost several hundred dollars more than a similarly equipped desktop model with a monitor, keyboard, and mouse. Furthermore, working long hours on a laptop with a small screen and keyboard may be more fatiguing than working on a desktop system. Therefore, if portability is not a requirement for your computer, you may find better value in a desktop model. Definition from the Tech Terms Computer Dictionary.

LCD Stands for "Liquid Crystal Display"

LCDs are super-thin displays that are used in laptop computer screens and flat panel monitors. Smaller LCDs are used in handheld TVs, PDAs, and portable video game devices. The image on an LCD screen is created by sandwiching an electrically reactive substance between two electrodes. This color of this substance can be changed by increasing or reducing the electrical current. Since LCD screens are based on the principle of blocking light (rather than emitting it), they use up much less power than standard CRT (Cathode-Ray Tube) monitors. Definition from the Tech Terms Computer Dictionary.


When you are browsing the Web and you see a highlighted and underlined word or phrase on a page, there is a good chance you are looking at a link. By clicking on a link, you can "jump" to a new Web page or a completely different Web site. While text links are typically blue and underlined, they can be any color and don't have to be underlined. Images can also serve as links to other Web pages. When you move the cursor over a link in a Web page, the arrow will turn into a little hand, letting you know that it is a link. The term "hypertext" comes from the way links can quickly send you to another Web destination. Definition from the Tech Terms Computer Dictionary.


This is the operating system that runs on Macintosh computers. It is pronounced, "mack-oh-es" The Mac OS has been around since the first Macintosh was introduced in 1984. Since then, it has been continually updated and many new features have been added to it. Each major OS release is signified by a new number (i.e. Mac OS 8, Mac OS 9).

Since the core of the Mac OS was nearly decades old, Apple decided to completely revamp the operating system. In March of 2001, Apple introduced a completely new version of the Mac OS that was written from the ground up. The company dubbed it "Mac OS X," correctly pronounced "Mac OS 10" Unlike earlier versions of the Mac OS, Mac OS X is based on the same kernel as Unix and has many advanced administrative features and utilities. Though the operating system is much more advanced than earlier versions of the Mac OS, it still has the same ease-of-use that people have come to expect from Apple software. Definition from the Tech Terms Computer Dictionary.


This is the name of the computers that are made by Apple Computer. The first Macintosh was introduced in 1984 and was seen as a major innovation in computing ease-of-use. The Macintosh was the first personal computer to use a graphical user interface (GUI), which allowed the user to interact with the operating system by using a mouse to click and drag objects. Since 1984, Apple has continually revised and upgraded the Macintosh product line and now makes both laptop and desktop versions of the Macintosh.

Apple also makes other equipment such as displays, MP3 players, and networking hardware, but the Macintosh is the heart and soul of the company. Macintosh computers run the Macintosh operating system, creatively named the "Mac OS" Definition from the Tech Terms Computer Dictionary.


Short for "malicious software" malware refers to software programs designed to damage or do other unwanted actions on a computer system. In Spanish, "mal" is a prefix that means "bad" making the term "badware" which is a good way to remember it (even if you're not Spanish). Common examples of malware include viruses, worms, trojan horses, and spyware.

Viruses, for example, can cause havoc on a computer's hard drive by deleting files or directory information. Spyware can gather data from a user's system without the user knowing it. This can include anything from the Web pages a user visits to personal information, such as credit card numbers.

It is unfortunate that there are software programmers out there with malicious intent, but it is good to be aware of the fact. You can install anti-virus and anti-spyware utilities on your computer that will seek and destroy the malicious programs they find on your computer. So join the fight against badware and install some protective utilities on your hard drive! Definition from the Tech Terms Computer Dictionary.

Megabyte (MB)

A megabyte is 2 to the 20th power, or 1,048,576 bytes. It can be estimated as 10 to the 6th power, or one million (1,000,000) bytes. A megabyte is 1,024 kilobytes and precedes the gigabyte unit of measurement. Large computer files are typically measured in megabytes. For example, a high-quality JPEG photo from a 6.3 megapixel digital camera takes up about 3MB of space. A four minute CD-quality audio clip takes up about 40MB of space and CDs can hold up to 700MB of space. Definition from the Tech Terms Computer Dictionary.


Just like humans, computers rely a lot on memory. They need to process and store data, just like we do. However, computers store data in digital format, which means the information can always be called up exactly the way it was stored. Also, unlike our memory, the computer's memory doesn't get worse over time. While memory can refer to any medium of data storage, it usually refers to RAM, or random access memory. When your computer boots up, it loads the operating system into its memory, or RAM.

This allows your computer to access system functions, such as handling mouse clicks and keystrokes, since the event handlers are all loaded into RAM. Whenever you open a program, the interface and functions used by that program are also loaded into RAM. RAM is a very high-speed type of memory, which makes it ideal for storing active programs and system processes. It is different than hard disk space in that RAM is made up of physical memory chips, while hard disks are magnetic disks that spin inside a hard drive.

Accessing RAM is much faster than accessing the hard disk because RAM access is based on electric charges, while the hard drive needs to seek to the correct part of the disk before accessing data. However, all the information stored in RAM is erased when the computer's power is turned off.

The hard disk, on the other hand, stores data magnetically without requiring any electrical power. For more information on the difference between RAM and hard disk space, view this Help Center article. Another common type of memory is flash memory, which is typically used for small devices such as digital cameras, USB keychain drives, and portable music players like the iPod nano.

This kind of memory, known as "electrically erasable programmable read-only memory" (EEPROM), is convenient for portable devices, since it stores information even when its power source is turned off, but is smaller and more resilient than a hard drive. To summarize, memory is a vital part of the way computers and many electronic devices function. While memory and RAM can often be used synonymously, it is good to know about other types of memory as well. Hopefully you will be able to store the information you've learned in your own memory. Definition from the Tech Terms Computer Dictionary.

Memory Card

A memory card or flash card is an electronic memory data storage device used for storing digital information. They are commonly used in many electronic devices, including digital cameras, mobile phones, laptop computers, MP3 players, and video game consoles. They are small, re-recordable, and they can retain data without power. Definition from Wikipedia.


The word modem is actually short for Modulator/Demodulator. (There's something you can really impress your friends with). A modem is a communications device that can be either internal or external to your computer. It allows one computer to connect another computer and transfer data over telephone lines or over your cable line. The original dial-up modems are becoming obsolete because of their slow speeds and are being replaced by the much faster cable and DSL modems. Definition from the Tech Terms Computer Dictionary.


The term "monitor" is often used synonymously with "computer screen" or "display" The monitor displays the computer's user interface and open programs, allowing the user to interact with the computer, typically using the keyboard and mouse. Older computer monitors were built using cathode ray tubes (CRTs), which made them rather heavy and caused them to take up a lot of desk space.

Most modern monitors are built using LCD technology and are commonly referred to as flat screen displays. These thin monitors take up much less space than the older CRT displays. This means people with LCD monitors have more desk space to clutter up with stacks of papers, pens, and other objects. "Monitor" can also be used as a verb. A network administrator may monitor network traffic, which means he watches the traffic to make sure the bandwidth usage is within a certain limit and checks to see what external sources may be attempting to access the network.

Software programs may monitor the system's CPU performance as well as RAM and hard disk usage. Finally, monitors also refer to speakers used for monitoring sound. Audio engineers typically use "studio monitors" to listen to recordings. These high-end speakers allow the engineers to accurately mix and master audio tracks. So a sound mixer could be monitoring a recording visually using a computer monitor, while monitoring the sound using audio monitors at the same. As you can tell, "monitor" serves as a rather multipurpose word. Definition from the Tech Terms Computer Dictionary.


The motherboard is the main circuit board of your computer and is also known as the mainboard or logic board. If you ever open your computer, the biggest piece of silicon you see is the motherboard. Attached to the motherboard, you'll find the CPU, ROM, memory RAM expansion slots, PCI slots, and USB ports.

It also includes controllers for devices like the hard drive, DVD drive, keyboard, and mouse. Basically, the motherboard is what makes everything in your computer work together. Each motherboard has a collection of chips and controllers known as the chipset. When new motherboards are developed, they often use new chipsets. The good news is that these boards are typically more efficient and faster than their predecessors. The bad news is that older components often do not work with new chipsets. Of course, if you are planning on upgrading multiple components, it may be more cost-effective to just buy a new computer. Definition from the Tech Terms Computer Dictionary.

MP3 Stands for "MPEG-1 Audio Layer-3"

MP3 is popular compressed audio file format that helped popularize digital music downloads beginning in the late 1990s. MP3 files are typically about one tenth the size of uncompressed WAVE or AIFF files, but maintain nearly the same CD-quality sound. Because of their small size and good fidelity, MP3 files have become a popular way to store music files on both computers and portable devices like the iPod. Several websites, like and, maintain extensive archives of MP3 files that users can download.

To listen to MP3s on your computer, you'll need an MP3 player like Nullsoft Winamp (for Windows) or Apple iTunes (for Mac and Windows). Most MP3 players also allow you to create MP3 files from CD audio tracks or other from other audio file types. Once you have converted your favorite songs to MP3 files, you can transfer them to a portable music player, like the Apple iPod, Microsoft Zune, or a music-enabled cell phone. You can also burn the MP3 files to a CD, which can be played in MP3-compatible CD players. Definition from the Tech Terms Computer Dictionary.


A Netbook is a simple and inexpensive laptop computer that has minimal capability and is primarily used for accessing the Internet. Netbooks that have many features are often difficult to distinguish from a laptop.


When you have two or more computers connected to each other, you have a network. The purpose of a network is to enable the sharing of files and information between multiple systems. The Internet could be described as a global network of networks. Computer networks can be connected through cables, such as Ethernet cables or phone lines, or wirelessly, using wireless networking cards that send and receive data through the air. Definition from the Tech Terms Computer Dictionary.

Operating System (OS)

Also known as an "OS" this is the software that communicates with computer hardware on the most basic level. Without an operating system, no software programs can run. The OS is what allocates memory, processes tasks, accesses disks and peripherials, and serves as the user interface.

Thanks to operating systems, like Windows, Mac OS, and Linux, developers can write code using a standard programming interface, or API. Without an operating system, programmers would have to write about ten times as much code to get the same results. Of course, some computer geniuses have to program the operating system itself. Definition from the Tech Terms Computer Dictionary.


A patch is a piece of software designed to fix problems with, or update a computer program or its supporting data. This includes fixing security vulnerabilities and other bugs, and improving the usability or performance. Though meant to fix problems, poorly designed patches can sometimes introduce new problems. Definition from Wikipedia.

PC Stands for "Personal computer"

PCs are are what most of us use on a daily basis for work or personal use. A typical PC includes a:
system unit, monitor, keyboard, and mouse.

Most PCs today also have a network or Internet connection, as well as ports for connecting peripheral devices, such as digital cameras, printers, scanners, speakers, external hard drives, and other components. Personal computers allow us to write papers, create spreadsheets, track our finances, play games, and do many other things. If a PC is connected to the Internet, it can be used to browse the Web, check e-mail, communicate with friends via instant messaging programs, and download files.

PCs have become such an integral part of our lives that it can be difficult to imagine life without them! While PC stands for "personal computer," the term can be a bit ambiguous. This is because Macintosh computers are often contrasted with PCs, even though Macs are also technically PCs.

However, Apple itself has used the term "PC" to refer to Windows-based machines, as opposed to its own computers, which are called "Macs." While the Mac/PC dilemma remains, PCs can always contrasted with other types of computers, such as mainframes and server computers, such as Web servers and network file servers. In other words, if you use a computer at home or at work, you can safely call it a PC. Definition from the Tech Terms Computer Dictionary.

Pen Drive

See Flash Drive

Power Supply

A power supply is a hardware component that supplies power to an electrical device. It receives power from an electrical outlet and converts the current from AC (alternating current) to DC (direct current), which is what the computer requires. It also regulates the voltage to an adequate amount, which allows the computer to run smoothly without overheating. The power supply an integral part of any computer and must function correctly for the rest of the components to work.

You can locate the power supply on a system unit by simply finding the input where the power cord is plugged in. Without opening your computer, this is typically the only part of the power supply you will see. If you were to remove the power supply, it would look like a metal box with a fan inside and some cables attached to it. Of course, you should never have to remove the power supply, so it's best to leave it in the case.

While most computers have internal power supplies, many electronic devices use external ones. For example, some monitors and external hard drives have power supplies that reside outside the main unit. These power supplies are connected directly to the cable that plugs into the wall. They often include another cable that connects the device to the power supply.

Some power supplies, often called "AC adaptors" are connected directly to the plug (which can make them difficult to plug in where space is limited). Both of these designs allow the main device to be smaller or sleeker by moving the power supply outside the unit.

Since the power supply is the first place an electronic device receives electricity, it is also the most vulnerable to power surges and spikes. Therefore, power supplies are designed to handle fluctuations in electrical current and still provide a regulated or consistent power output. Some include fuses that will blow if the surge is too great, protecting the rest of the equipment. After all, it is much cheaper to replace a power supply than an entire computer. Still, it is wise to connect all electronics to a surge protector or UPS to keep them from being damaged by electrical surges. Definition from the Tech Terms Computer Dictionary.


This little chip is the heart of a computer. Also referred to as the "microprocessor" the processor does all the computations such as adding, subtracting, multiplying, and dividing. In PCs, the most popular microprocessor used is the Intel Pentium chip, whereas Macintosh computers use the PowerPC chip (developed by Motorola, IBM, and Apple).

The speed of a computer's processor is measured in megahertz, or cycles per second. But higher megahertz doesn't always mean better performance. Though a 600-MHz chip has a clock speed that is twice as fast as a 300-Mhz chip, it doesn't mean that the computer with the 600-Mhz chip will run twice as fast.

This is because the speed of a computer is also influenced by other factors, such as the efficiency of the processor, the bus architecture, the amount of memory available, and the software that is running on the computer. Some processors can complete more operations per clock cycle than other processors, making them more efficient than other processors with higher clock speeds. This is why the PowerPC chip is typically faster than Pentium chips at that are clocked at higher megahertz. Definition from the Tech Terms Computer Dictionary.


Program is a common computer term that can be used as both a noun and a verb. A program (noun) is executable software that runs on a computer. It is similar to a script, but is often much larger in size and does not require a scripting engine to run. Instead, a program consists of compiled code that can run directly from the computer's operating system.

Examples of programs include Web browsers, word processors, e-mail clients, video games, and system utilities. These programs are often called applications, which can be used synonymously with "software programs" On Windows, programs typically have an .EXE file extension, while Macintosh programs have an .APP extension.

When "program" is used as verb, it means to create a software program. For example, programmers create programs by writing code that instructs the computer what to do. The functions and commands written by the programmer are collectively referred to as source code. When the code is finished, the source code file or files are compiled into an executable program. Definition from the Tech Terms Computer Dictionary.

RAM Stands for "Random Access Memory"

and is pronounced like the male sheep. RAM is made up of small memory chips that form a memory module. These modules are installed in the RAM slots on the motherboard of your computer. Every time you open a program, it gets loaded from the hard drive into the RAM. This is because reading data from the RAM is much faster than reading data from the hard drive.

Running programs from the RAM of the computer allows them to function without any lag time. The more RAM your computer has, the more data can be loaded from the hard drive into the RAM, which can effectively speed up your computer. In fact, adding RAM can be more beneficial to your computer's performance than upgrading the CPU.

To check how much RAM a Windows computer has, open the "System" Control Panel. This can be done by right-clicking "My Computer" and selecting "Properties..." To view how much RAM is installed in a Macintosh computer, select "About This Mac" from the Apple Menu. Definition from the Tech Terms Computer Dictionary.


Safari is the web browser that comes standard on a Mac.


Same as monitor

SD Stands for "Secure Digital"

It is a type of memory card used for storing data in devices such as digital cameras, PDAs, mobile phones, portable music players, and digital voice recorders. The card is one of the smaller memory card formats, measuring 24mm wide by 32mm long and is just 2.1mm thick. To give the cards some orientation, the top-rght corner of each SD card is slanted. Even though the cards are extremely small, as of late 2004, they can hold up to 8GB of data.

Part of the reason the cards are called "Secure Digital" cards is because the cards have a copyright protection feature built in. The security feature, called "key revocation" means protected data on the card can only be read by specific devices. The cards can have both secured and unsecured areas on them for copyrighted and non-copyrighted data. Definition from the Tech Terms Computer Dictionary.


As the name implies, this is software that "spies" on your computer. Nobody likes to be spied on, and your computer doesn't like it either. Spyware can capture information like Web browsing habits, e-mail messages, usernames and passwords, and credit card information. If left unchecked, the software can transmit this data to another person's computer over the Internet. So how does spyware get on your computer? Just like viruses, spyware can be installed when you open an e-mail attachment containing the malicious software. It can also be installed when you install another program that has a spyware installer attached to it. Because of the insidious nature of spyware, most people don't even know when spyware is on their computer.

Fortunately, you can purchase anti-spyware utilities that will search for spyware on your computer and stomp the unwanted software out of your system. A good way to prevent spyware from infecting your computer is to install a security program that lets you know when any program is being installed, so that you can choose to authorize or stop the installation. Definition from the Tech Terms Computer Dictionary.

Start Menu

The start menu is a button at the lower left hand part of the screen in Windows that provides a starting point for finding and running an application.


The systray, short for "system tray" is located on the right side of the Windows toolbar. It is the collection of small icons on the opposite side of the Start Menu. The volume control and the date, time are default items in the systray and many more can be added. Some common icons that get placed in the systray are virus-scan, mouse, and instant messenger icons. They usually get put in the systray (whether you like it or not) when their respective programs are installed.

The nice thing about the systray is that it allows quick and easy access to programs and control settings. Most systray icons will open a control panel or program when double-clicked. However, if you install too many of them, the area can get so cluttered, you may find it easier to just browse your hard drive and open the program. Definition from the Tech Terms Computer Dictionary.

Task Bar

The task bar was introduced with Windows 95 and has been part of every version of Windows since then. It is the bar that spans the bottom of the screen and contains the Start button on the left side and the systray on the right. The task bar also includes the current time on the far right side and can hold shortcuts to programs directly to the right of the Start button.

Most of the task bar, however, contains shortcuts to open windows. Whenever you open a program or window, it shows up in the task bar. So if you have Internet Explorer and Microsoft Word open, there will be at least two items in the middle area of the task bar. Since each window gets its own location in the task bar, if there are two Microsoft Word documents open and three Internet Explorer windows open, there will be a total of five items in the task bar. When you click on a window title in the task bar, that window will become active and show up in front of other open windows. You can also cycle through the task bar items by holding the Alt key and pressing Tab a few times. Definition from the Tech Terms Computer Dictionary.

Terabyte (TB)

A terabyte is 2 to the 40th power, or 1,099,511,627,776 bytes. It can be estimated as 10 to the 12th power, or 1,000,000,000,000 bytes. A terabyte is 1,024 gigabytes and precedes the petabyte unit of measurement. While today's consumer hard drives are typically measured in gigabytes, Web servers and file servers may have several terabytes of space. A single 500GB hard drive can also be called a half-terabyte drive.

The prefix "tera" comes from the Greek word meaning "monster" So, if you have a 500GB hard drive, you could say you have half a monsterbyte of disk space. If nothing else, it sure sounds impressive. Definition from the Tech Terms Computer Dictionary.

Thumb Drive

See Flash Drive

USB Stands for "Universal Serial Bus"

USB is the most common type of computer port used in today's computers. It can be used to connect keyboards, mice, game controllers, printers, scanners, digital cameras, and removable media drives, just to name a few. With the help of a few USB hubs, you can connect up to 127 peripherals to a single USB port and use them all at once (though that would require quite a bit of dexterity).

USB is also faster than older ports, such as serial and parallel ports. The USB 1.1 specification supports data transfer rates of up to 12Mb/sec and USB 2.0 has a maximum transfer rate of 480 Mbps. Though USB was introduced in 1997, the technology didn't really take off until the introduction of the Apple iMac (in late 1998) which used USB ports exclusively. It is somewhat ironic, considering USB was created and designed by Intel, Compaq, Digital, and IBM. Over the past few years, USB has become a widely-used cross-platform interface for both Macs and PCs. Definition from the Tech Terms Computer Dictionary.

Video Chat

Video chat refers to using video to supplement audio when speaking to someone over the phone thus allowing the two parties to see each other while they speak. Typically, people will video chat on their computers using low cost webcams and free software programs that establish the call over the Internet. Modern video chat technology can provide very high quality at a very low cost, thus making it accessible to most computer and Internet users.


Like a biological virus, a computer virus is something you don't want to get. Computer viruses are small programs or scripts that can negatively affect the health of your computer. These malicious little programs can create files, move files, erase files, consume your computer's memory, and cause your computer not to function correctly. Some viruses can duplicate themselves, attach themselves to programs, and travel across networks. In fact opening an infected e-mail attachment is the most common way to get a virus.

We all know it's hard enough to get a computer to work well when it is healthy, let alone when it has been attacked by a virus. Therefore, it is better to prevent an attack than to try and cure it. There are many anti-virus programs available that scan incoming files for viruses before they can cause damage to your computer. Some of these programs include Norton AntiVirus?, McAfee VirusScan?, and Virex?. It is a good idea to have one of these programs on your computer to prevent a virus attack. It is also important to update your virus definitions file at least once a month so that your anti-virus program can check for all the latest viruses. It's a lot like having a glass of orange juice every morning it keeps your computer's immune system strong and healthy. Definition from the Tech Terms Computer Dictionary.

Web Browser

You are probably using a browser to read this right now. A Web browser, often just called a "browser" is the program people use to access the World Wide Web. It interprets HTML code including text, images, hypertext links, Javascript, and Java applets. After rendering the HTML code, the browser displays a nicely formatted page. Some common browsers are Microsoft Internet Explorer, Netscape Communicator, and Apple Safari. Definition from the Tech Terms Computer Dictionary.

Web Page

Web pages are what make up the World Wide Web. These documents are written in HTML (hypertext markup language) and are translated by your Web browser. Web pages can either be static or dynamic. Static pages show the same content each time they are viewed. Dynamic pages have content that can change each time they are accessed.

These pages are typically written in scripting languages such as PHP, Perl, ASP, or JSP. The scripts in the pages run functions on the server that return things like the date and time, and database information. All the information is returned as HTML code, so when the page gets to your browser, all the browser has to do is translate the HTML. Please note that a Web page is not the same thing as a Web site.

A Web site is a collection of pages. A Web page is an individual HTML document. This is a good distinction to know, as most techies have little tolerance for people who mix up the two terms. Definition from the Tech Terms Computer Dictionary.

Webcam The term webcam is a combination of "Web" and "video camera" The purpose of a webcam is, not surprisingly, to broadcast video on the Web. Webcams are typically small cameras that either attach to a user's monitor or sit on a desk. Most webcams connect to the computer via USB, though some use a Firewire connection. Webcams typically come with software that allows the user to record video or stream the video on the Web. If the user has a website that supports streaming video, other users can watch the video stream from their Web browsers.

Webcams can also be used for video chat sessions with other people. Instead of broadcasting the video on the Web, users can set up a video chat session with one or more friends and have a conversation with live audio and video.

For example, Apple's iSight camera, which is built into Apple laptops and iMacs, allows users to video chat using the iChat instant messaging program. Several other chat programs also work with webcams, allowing users to set up video chat sessions with friends. Since streaming video over the Internet requires a lot of bandwidth, the video stream is typically compressed to reduce the "choppiness" of the video.

The maximum resolution of a webcam is also lower than most handheld video cameras, since higher resolutions would be reduced anyway. For this reason, webcams are relatively inexpensive compared to most video cameras. And while they may not be ideal for filming a movie, webcams are great for video chat sessions with friends. Definition from the Tech Terms Computer Dictionary.


A website, or Web site, is not the same thing as a Web page. Though the two terms are often used interchangeably, they should not be. So what's the difference? To put it simply, a Web site is a collection of Web pages.

For example, is a Web site, but there are millions of Web pages that make up the site. Knowing the difference between these two terms can save you a lot of embarrassment. Definition from the Tech Terms Computer Dictionary.

Wi-Fi Short for "Wireless Fidelity"

Wi-Fi refers to wireless networking technology that allows computers and other devices to communicate over a wireless signal. It describes all network components that are based on one of the 802.11 standards, including 802.11a, 802.11b, 802.11g, and 802.11n. These standards were developed by the IEEE and adopted by the Wi-Fi Alliance, which trademarked the name "Wi-Fi". Wi-Fi is the standard way computers connect to wireless networks.

Nearly all computers now have built-in Wi-Fi cards that allows users to search for and connect to wireless routers. Many mobile devices, video game systems, and other standalone devices also include Wi-Fi capability, enabling them to connect to wireless networks as well. These devices may be able to connect to the Internet using a Wi-Fi signal. However, it is important to understand that the Wi-Fi connection only exists between the device and the router. Most routers are connected to a DSL or cable modem, which provides Internet access to all connected devices.

Since Wi-Fi is a wireless networking standard, any device with a "Wi-Fi Certified" wireless card should be recognized by any "Wi-Fi Certified" access point, and vice-versa. However, wireless routers can be configured to only work with a specific 802.11 standard, which may prevent older equipment from communicating with the router. For example, some 802.11n routers can either be configured to only work with 802.11n devices. If this option is chosen, 802.11g devices will not be able to connect to the router, even though they are Wi-Fi certified. Definition from the Tech Terms Computer Dictionary.


Microsoft Windows is the most popular operating system for personal computers. There are several versions of the Windows operating system, including Windows XP (for home users) and Windows 2000 (for professional users). Earlier versions of Windows include Windows 3.1, 95, 98, ME, and NT. All Windows platforms use a graphical user interface (GUI), like the Mac OS, and also offer a command-line interface for typing text commands. Definition from the Tech Terms Computer Dictionary.

Windows Explorer

Windows Explorer is a program that allows the user to navigate and access all of the files on their computer. Windows Explorer comes standard with all versions of Microsoft Windows.