Fiber-Optic Cable

his is a cable made up of super-thin filaments of glass or other transparent materials that can carry beams of light. Because a fiber-optic cable is light-based, data can be sent through it at the speed of light. Using a laser transmitter that encodes frequency signals into pulses of light, ones and zeros are sent through the cable. The receiving end of the transmission translates the light signals back into data which can be read by a computer.

Because fiber-optics are based entirely on beams of light, they are less susceptible to noise and interference than than other data-transfer mediums such as copper wires or telephone lines. However, the cables are fragile and are usually placed underground, which makes them difficult and expensive to install. Some fiber-optic cables are installed above ground, but if they break, they often need to be completely replaced, which is not cheap. While copper wires can be spliced and mended as many times as needed, it is much harder to fix glass fiber-optic cables.

URL

Stands for "Uniform Resource Locator." A URL is the address of a specific Web site or file on the Internet. It cannot have spaces or certain other characters and uses forward slashes to denote different directories. Some examples of URLs are http://www.cnet.com/, http://web.mit.edu/, and ftp://info.apple.com/. As you can see, not all URLs begin with "http". The first part of a URL indicates what kind of resource it is addressing. Here is a list of the different resource prefixes:

• http - a hypertext directory or document (such as a Web page)
• ftp - a directory of files or an actual file available to download
• gopher - a gopher document or menu
• telnet - a Unix-based computer system that you can log into
• news - a newsgroup
• WAIS - a database or document on a Wide Area Information Search database
• file - a file located on your hard drive or some other local drive

The second part of a URL (after the "://") contains the address of the computer being located as well as the path to the file. For example, in "http://www.cnet.com/Content/Reports/index.html," "www.cnet.com" is the address or domain name of the host computer and "/Content/Reports/index.html" is the path to the file. When a address ends with a slash and not something like ".html" or ".php," the Web server typically defaults to a file in the current directory named "index.html," "index.htm," or "index.php." So, if you type in "http://www.apple.com/" and "http://www.apple.com/index.html," you should get the same page. Go ahead and try it if you have nothing better to do.

Blog

Short for "Web Log," this term refers to a list of journal entries posted on a Web page. Anybody who knows how to create and publish a Web page can publish their own blog. Some Web hosts have made it even easier by creating an interface where users can simply type a text entry and hit "publish" to publish their blog.

Because of the simplicity of creating a blog, many people (often young kids and adults) have found a new presence on the Web. Instead of writing confidential entries in a book that no one is supposed to see, people now can share their personal feelings and experiences with thousands of people around the world. Blogs are typically updated daily, monthly, or anywhere in between. "Blog" may also be used as a verb, as in "Wow, Matt sure blogged a lot last week."

Applet

This a Java program that can be embedded in a Web page. The difference between a standard Java application and a Java applet is that an applet can't access system resources on the local computer. System files and serial devices (modems, printers, scanners, etc.) cannot be called or used by the applet. This is for security reasons -- nobody wants their system wiped out by a malicious applet on some wacko's Web site. Applets have helped make the Web more dynamic and entertaining and have given a helpful boost to the Java programming language

Bit

The computer term "bit" comes from the phrase "Binary DigIT," which is different than that thing you put around a horse's mouth. A bit is a single digit number in base-2 (a zero or a one) and is the smallest unit of computer data. A full page of text is composed of about 16,000 bits.

It is important not to confuse bits with bytes. Both are used to measure amounts of data, but it takes eight bits to make one byte. The most common area where bits are used intstead of bytes is in measuring bandwidth (in bits per second). Why? Probably because it makes your Internet connection sound faster than it really is.

Byte

A byte is a unit of measurement used to measure data. One byte contains eight binary bits, or a series of eight zeros and ones. Therefore, each byte can be used to represent 2^8 or 256 different values.

The byte was originally developed to store a singlecharacter, since 256 values is sufficient to represent all standard lowercase and uppercase letters, numbers, and symbols. However, since some languages have more than 256 characters, modern character encodingstandards, such as UTF-16, use two bytes, or 16 bits for each character.

While the byte was originally designed to measure character data, it is now the fundamental unit of measurement for all data storage. For example, a kilobyte contains 2^10 or 1,024 bytes. Amegabyte contains 1,024 x 1,024, or 1,048,576 bytes. Since bytes are so small, they are most often used to measure specific data within a file, such as pixels or characters. Even the smallest files are typically measured in kilobytes, while data storage limits are often measured in gigabytesor terabytes.

Worm

Worm has two widely different definitions. One refers to a computer virus and the other is an optical storage technology: 1) A type of computer virus

Just like regular worms tunnel through dirt and soil, computer worms tunnel through your computer's memory and hard drive. A computer worm is a type ofvirus that replicates itself, but does not alter any files on your machine. However, worms can still cause havoc by multiplying so many times that they take up all your computer's available memory or hard disk space. If a worm consumes your memory, your computer will run very slowly and possibly even crash. If the worm affects your hard disk space, your computer will take a long time to access files and you will not be able to save or create new files until the worm has been eradicated.

Worms are hard to detect because they are typically invisible files. They often go unnoticed until your computer begins to slow down or starts having other problems. Unlike viruses and Trojan horses, worms can replicate themselves and travel between systems without any action from the user. For these reasons, it is good to have an antivirus program installed on your system that can detect and remove worms before they have a chance to replicate or spread to other computers. Security updates such as Windows Update also patch security holes that allow worms to infect your computer. So keep your security updates and virus definitions up-to-date and you should be able to keep your computer worm-free.

2) An optical storage technology

WORM can also mean "Write Once, Read Many." It is an optical storage technology that allows a disc to be written only once but read an unlimited number of times. WORM devices were introduced in the 1970's and gained popularity as a way of archiving data. The storage capacity of WORM discs began around 140MB, but increased to more than 3.0GB over the past few decades. Yet the WORM technology has no standard format, so WORM discs are only compatible with the drives that wrote them. This limitation has kept WORM equipment relatively expensive and has kept the technology from gaining widespread acceptance.

Today, most optical drives are based on either CD-R or DVD-R technology. Unlike WORM discs, CD-Rs and DVD-Rs can typically be read by any CD or DVD drive, regardless of the manufacturer. Because of their improved compatibility and lower costs, writable CDs and DVDs have all but replaced WORM media.