Glossary

Mathematically, a vector is a quantity, defined by both magnitude and direction. For example, a vector could be illustrated by an 1 inch arrow pointing at a 30 degree angle. Another vector may be 2.5 inches and point at a 160 degree angle. In the computer world, vectors are used to define paths in certain types of images, such as EPS files and Adobe Illustrator documents. These images are often called vector graphics since they are comprised of vectors, or paths, instead of dots. Vector graphics can be scaled larger or smaller without losing quality.

In computer science, a vector may refer to a type of one dimensional array. For example, a vector called "fibonacci" that stores the first six values of the Fibonacci sequence would be defined as follows:

fibonacci[0] = 0, fibonacci[1] = 1, fibonacci[2] = 1, fibonacci[3] = 2, fibonacci[4] = 3, fibonacci[5] = 5

Vectors are similar to arrays, but unlike arrays, vectors use their own memory management mechanisms. Arrays are restricted to the memory structure supplied by the programming language they are created in, typically called a stack. Vectors have a more dynamic structure, often referred to as a heap, which gives them greater flexibility in how they use memory. While an array uses a static amount of memory, the memory used by the vector can be increased or decreased as elements are added or removed from the vector.

Unlike JPEGs, GIFs, and BMP images, vector graphics are not made up of a grid of pixels. Instead, vector graphics are comprised of paths, which are defined by a start and end point, along with other points, curves, and angles along the way. A path can be a line, a square, a triangle, or a curvy shape. These paths can be used to create simple drawings or complex diagrams. Paths are even used to define the characters of specific typefaces.

Because vector-based images are not made up of a specific number of dots, they can be scaled to a larger size and not lose any image quality. If you blow up a raster graphic, it will look blocky, or "pixelated." When you blow up a vector graphic, the edges of each object within the graphic stay smooth and clean. This makes vector graphics ideal for logos, which can be small enough to appear on a business card, but can also be scaled to fill a billboard. Common types of vector graphics include Adobe Illustrator, Macromedia Freehand, and EPS files. Many Flash animations also use vector graphics, since they scale better and typically take up less space than bitmap images.

File extensions: .AI, .EPS, .SVG, .DRW

Stands for "Video Graphics Array." It is the standard monitor or display interface used in most PCs. Therefore, if a montior is VGA-compatible, it should work with most new computers. The VGA standard was originally developed by IBM in 1987 and allowed for a display resolution of 640x480 pixels. Since then, many revisions of the standard have been introduced. The most common is Super VGA (SVGA), which allows for resolutions greater than 640x480, such as 800x600 or 1024x768. A standard VGA connection has 15 pins and is shaped like a trapezoid.

An unauthorized piece of computer code attached to a computer program or portions of a computer system that secretly copies itself from one computer to another by shared discs and over telephone and cable lines. It can destroy information stored on the computer, and in extreme cases, can destroy operability. Computers can be protected from viruses if the operator utilizes good virus prevention software and keeps the virus definitions up to date. Most viruses are not programmed to spread themselves. They have to be sent to another computer by e-mail, sharing, or applications.The worm is an exception, because it is programmed to replicate itself by sending copies to other computers listed in the e-mail address book in the computer. There are many kinds of viruses, for example:

• Boot viruses place some of their code in the start-up disk sector to automatically execute when booting. Therefore, when an infected machine boots, the virus loads and runs.

• File viruses attached to program files (files with the extension .exe). When you run the infected program, the virus code executes.

• Macro viruses copy their macros to templates and/or other application document files.

• Trojan Horse is a malicious, security-breaking program that is disguised as something being such as a screen saver or game.

• Worm launches an application that destroys information on your hard drive. It also sends a copy of the virus to everyone in the computer's e-mail address book.

Stands for "Virtual Private Network" (not a successor to the UPN television network). VPN is a network term that most computer users don't need to know, but at least you can impress your friends by talking about it. A virtual private network is "tunneled" through a wide area network WAN such as the Internet. This means the network does not have to be located in one physical location like a LAN. However, by using encryption and other security measures, a VPN can scramble all the data sent through the wide area network, so the network is "virtually" private.

Businesses often use VPNs to communicate across multiple locations. For example, a large company that has offices in several cities may need to send data to the different locations via the Internet. To keep the information secure, the company might set up a VPN with an encrypted connection. This is similar to having a secure intranet over the Internet. On a smaller scale, individual users may have a VPN account with their company, which allows them to connect to their office computer from their home or another location. This is especially helpful for business travelers who need to access office data from their laptops.