computer glossary of terms.
Active Channels An Active Channel is what Microsoft calls a Web site
that has been enabled for push delivery to Internet Explorer 4.0 browsers. To create a
channel, developers write and upload a CDF (channel definition format) file to their Web
site; new content is delivered to users automatically when the site is updated. Developers
and subscribers can control the update frequency; which channels, subchannels, and items
(sections) are subscribed to; and other channel characteristics. Most Active Channels use
dynamic HTML (DHTML) and other effects to spice up content and make it more interactive.
Analog The traditional method of modulating radio signals so that they can carry information. Amplitude modulation (AM) and frequency modulation (FM) are the two most common methods of analog modulation. Today, most U.S. cellular systems carry phone conversations using analog; the transition to digital transmissions is happening slowly
ASCII -- (American Standard Code for Information Interchange) This is the defacto world-wide standard for the code numbers used by computers to represent all the upper and lower-case Latin letters, numbers, punctuation, etc. There are 128 standard ASCII codes each of which can be represented by a 7 digit binary number: 0000000 through 1111111.
AT commands AT is a contraction of attention, a command used to
program SmartModems from Hayes Microcomputer Products. AT commands program a variety of
modem hardware settings and were adopted by other modem manufacturers who wanted to market
their wares with the coveted phrase Hayes-compatible. At one time, you couldn't call
yourself an online aficionado if you didn't know that ATL0 turned your modem speaker way
down and ATM0 turned it off. Now the commands are usually hidden under a menu option in
your communication software.
BIOS basic input/output system The BIOS is what's coded into a
PC's ROM to provide the basic instructions for controlling system hardware. The operating
system and application programs both directly access BIOS routines to provide better
compatibility for such functions as screen display. Some makers of add-in boards such as
graphics accelerator cards provide their own BIOS modules that work in conjunction with
(or replace) the BIOS on the system's motherboard.
Boolean English mathematician George Boole (1815-64) founded a field of mathematical and philosophical study called symbolic logic. His name is now used most often to describe a subset of symbolic logic: constructing database queries.
Whenever you see a Web search tool or database query system that allows you to use AND,
OR, and NOT to hone your search, the chances are it uses Boolean techniques. The most
common Boolean operators are AND (you're looking for all terms), OR (you're looking for at
least one of the terms), and NOT (you're excluding a term). You'll always see the
operators referred to in uppercase letters, although you usually don't need to enter them
that way to make a Boolean search work properly. Also, the Boolean operator AND doesn't
work like a normal English and. For example, a Boolean search through a database of rock
musicians for members of the Beatles AND Wings would turn up only Paul McCartney.
Byte A set of Bits that represent a single character. Usually there are 8 Bits in a Byte, sometimes more, depending on how the measurement is being made.
cache Caches come in many types, but they all work the same way: they store information where you can get to it fast. A Web browser cache stores the pages, graphics, sounds, and URLs of online places you visit on your hard drive; that way, when you go back to the page, everything doesn't have to be downloaded all over again. Since disk access is much faster than Internet access, this speeds things up. Of course, disk access is slower than RAM access, so there's also disk caching, which stores information you might need from your hard disk in faster RAM.
Cardbus Cardbus is a specification that allows PCMCIA cards to transfer data at rates exceeding 100MB/sec. Older, 16-bit PCMCIA cards transfer data at a rate of 20MB/sec.
Certificate Authority An issuer of Security Certificates used in SSL connections. CGI -- (Common Gateway Interface) A set of rules that describe how a Web Server communicates with another piece of software on the same machine, and how the other piece of software (CGI program) talks to the web server. Any piece of software can be a CGI program if it handles input and output according to the CGI standard. cgi-bin The most common name of a directory on a web server in which CGI programs are stored.
Client A software program that is used to contact and obtain data from a Server software program on another computer, often across a great distance. Each Client program is designed to work with one or more specific kinds of Server programs, and each Server requires a specific kind of Client. A Web Browser is a specific kind of Client.
co-location Most often used to refer to having a server that belongs to one
person or group physically located on an Internet-connected network that belongs to
another person or group. Usually this is done because the server owner wants their machine
to be on a high-speed Internet connection and/or they do not want the security risks of
having the server on thier own network.
COM port Although it's in all capital letters, COM is not an acronym. It's a contraction of communications, and it's used to describe the serial port on a PC. COM is generally used in conjunction with a number, as in COM1, COM2, COM3, or COM4.
Domain Name The unique name that identifies an Internet site. Domain Names always have 2 or more parts, separated by dots. The part on the left is the most specific, and the part on the right is the most general. A given machine may have more than one Domain Name but a given Domain Name points to only one machine. For example, the domain names: can all refer to the same machine, but each domain name can refer to no more than one machine. Usually, all of the machines on a given Network will have the same thing as the right-hand portion of their Domain Names (matisse.net in the examples above). It is also possible for a Domain Name to exist but not be connected to an actual machine. This is often done so that a group or business can have an Internet e-mail address without having to establish a real Internet site. In these cases, some real Internet machine must handle the mail on behalf of the listed Domain Name.
DNS domain name system When you send email or point a browser to an Internet domain such as cnet.com, the domain name system translates the names into Internet addresses (a series of numbers looking something like this: 184.108.40.206). The term refers to two things: the conventions for naming hosts and the way the names are handled across the Internet.
DSL -- (Digital Subscriber Line) A method for moving data over regular phone
lines. A DSL circuit is much faster than a regular phone connection, and the wires coming
into the subscriber's premises are the same (copper) wires used for regular phone service.
A DSL circuit must be configured to connect two specific locations, similar to a leased
line (howeverr a DSL circuit is not a leased line. A common configuration of DSL allows
downloads at speeds of up to 1.544 megabits (not megabytes) per second, and uploads at
speeds of 128 kilobits per second. This arrangement is called ADSL: Asymmetric Digital
Extranet An intranet that is accesible to computers that are not hysically part
of a companys' own private network, but that is not accessible to the general public, for
example to allow vendors and business partners to access a company web site. Often an
intranet will make use of a Virtual Private Network. (VPN.)
firewall If you want to protect any networked server from damage
(intentional or otherwise) by those who log in to it, you put up a firewall. This could be
a dedicated computer equipped with security measures such as a dial-back feature, or it
could be software-based protection called defensive coding. A combination of
hardware and software that separates a Network into two or more parts for security
Gateway The technical meaning is a hardware or software set-up that
translates between two dissimilar protocols, for example America Online has a gateway that
translates between its internal, proprietary e-mail format and Internet e-mail format.
Another, sloppier meaning of gateway is to describe any mechanism for providing access to
another system, e.g. AOL might be called a gateway to the Internet.
hit As used in reference to the World Wide Web, hit means a single request from
a web browser for a single item from a web server; thus in order for a web browser to
display a page that contains 3 graphics, 4 hits would occur at the server: 1 for the HTML
page, and one for each of the 3 graphics.
The "hyper" in Hypertext comes from the fact that in HTML you can specify that a block of text, or an image, is linked to another file on the Internet. HTML files are meant to be viewed using a "Web Browser".
HTTP -- (HyperText Transfer Protocol) The protocol for moving hypertextfiles
across the Internet. Requires a HTTP client program on one end, and an HTTP server program
on the other end. HTTP is the most important protocol used in the World Wide Web (WWW).
Using IMAP an email client program can not only retrieve email but can also manipulate message stored on the server, without having to actually retrieve the messages. So messages can be deleted, have their status changed, multiple mail boxes can be managed, etc.
Intranet A private network inside a company or organization that uses the same
kinds of software that you would find on the public Internet, but that is only for
internal use. Compare with extranet.
Every machine that is on the Internet has a unique IP number - if a machine does not have an IP number, it is not really on the Internet. Many machines (especially servers) also have one or more Domain Names that are easier for people to remember.
ISDN -- (Integrated Services Digital Network) Basically a way to move more dataover existing regular phone lines. ISDN is available to much of the USA and in most markets it is priced very comparably to standard analog phone circuits. It can provide speeds of roughly 128,000 bits-per-second over regular phone lines. In practice, most people will be limited to 56,000or 64,000 bits-per-second. Unlike DSL, ISDN can be used to connect to many different locations, one at a time, just like a regular telephone call, as long the other location also has ISDN.
ISP -- (Internet Service Provider) An institution that provides access to the Internet in some form, usually for money. Java Java is a network-friendly programming language invented by Sun Microsystems.
Java is often used to build large, complex systems that involve several different computers interacting across networks, for example transaction processing systems. Java is also becoming popular for creating programs that run in small electronic devicws, such as mobile telephones. A very common use of Java is to create programs that can be safely downloaded to your computer through the Internet and immediately run without fear of viruses or other harm to your computer or files. Using small Java programs (called "Applets"), Web pages can include functions such as animations,calculators, and other fancy tricks.
Kilobyte A thousand bytes. Actually, usually 1024 (210)
Megabyte A million bytes. Actually, technically, 1024 kilobytes.
Modem -- (MOdulator, DEModulator) A device that connects a computer to a phone line. A telephone for a computer. A modem allows a computer to talk to other computers through the phone system. Basically, modems do for computers what a telephone does for humans. MOO -- (Mud, Object Oriented) One of several kinds of multi-user role-playing environments. Mosaic The first WWW browser that was available for the Macintosh, Windows,and UNIX all with the same interface. Mosaic really started the popularity of the Web. The source-code to Mosaic was licensed by several companies and used to create many other web browsers.
Mosaic was developed at the National Center for Supercomputing Applications (NCSA), at the Univeristy of Urbana-Champange in Illinois, USA. The first version was released in late 1993.
MUD -- (Multi-User Dungeon or Dimension) A (usually text-based)
multi-user simulation environment. Some are purely for fun and flirting, others are used
for serious software development, or education purposes and all thatlies in between. A
significant feature of most MUDs is that users can create things that stay after they
leave and which other users can interact within their absence, thus allowing a world to be
built gradually and collectively. MUSE -- (Multi-User Simulated Environment) One
kind of MUD - usually with little or no violence.
ping To check if a server is running. From the sound that a sonar
systems makes in movies, you know, when they are searching for a submarine.
Port 3 meanings. First and most generally, a place where information goes into or out of a computer, or both. E.g. the serial port on a personal computer is where a modem would be connected. On the Internet port often refers to a number that is part of a URL, appearing after a colon (:) right after the domain name. Every service on an Internet server listens on a particular port number on that server. Most services have standard port numbers, e.g. Web servers normally listen on port 80. Services can also listen on non-standard ports, in which case the port number must be specified in a URL when accessing the server, so you might see a URL of the form: This shows a gopher server running on a non-standard port (the standard gopher port is 70). Finally, port also refers to translating a piece of software to bring it from one type of computer system to another, e.g. to translate a Windows program so that is will run on a Macintosh.
Portal Usually used as a marketing term to described a Web site
that is or is intended to be the first place people see when using the Web. Typically a
"Portal site" has a catalog of web sites, a search engine, or both. A Portal
site may also offer email and other service to entice people to use that site as their
main "point of entry" (hence "portal") to the Web.
Proxy Server A Proxy Server sits in between a Client and the "real" Server that a Client is trying to use. Client's are sometimes configured to use a Proxy Server, usually an HTTP server. The clients makes all of it's requests from the Proxy Server, which then makes requests from the "real" server and passes the result back to the Client. Sometimes the Proxy server will store the results and give a stored result instead of making a new one (to reduce use of a Network). Proxy servers are commonly established on Local Area Networks
Router A special-purpose computer (or software package) that
handles the connection between 2 or more Packet-Switched networks. Routers spend all their
time looking at the source and destination addresses of the packets passing through them
and deciding which route to send them on.
A single server machine can (and often does) have several different server software packages running on it, thus providing many different servers to clients on the network.
SLIP -- (Serial Line Internet Protocol) A standard for using a
regular telephone line (a serial line) and a modem to connect a computer as a realInternet
site. SLIP has largely been replaced by PPP. SMDS -- (Switched Multimegabit Data
Service) A standard for very high-speed data transfer.
SNMP -- (Simple Network Management Protocol) A set of standards for communication with devices connected to a TCP/IP network. Examples of these devices include routers, hubs, and switches.
Spam (or Spamming) An inappropriate attempt to use a mailing list,
or USENET or other networked communications facility as if it was a broadcast medium
(which it is not) by sending the same message to a large number of people who didn?t ask
for it. The term probably comes from a famous Monty Python skit which featured the word
spam repeated over and over. The term may also have come from someone?s low opinion of the
food product with the same name, which is generally perceived as a generic content-free
waste of resources. (Spam is a registered trademark of Hormel Corporation, for its
processed meat product.)
SSL -- (Secure Socket Layer) A protocol designed by Netscape
Communications to enable encrypted, authenticated communications across the Internet.
URL -- (Uniform Resource Locator) The term URL is
basically synonymous with URI. URI has replaced URL in technical specifications.
A virus requires the presence of some other program to replicate itself. Typically viruses spread by attaching themselves to programs and in some cases files, for example the file formats for Microsoft word processor and spreadsheet programs allow the inclusion of programs called "macros" which can in some cases be a breeding ground for viruses. VPN -- (Virtual Private Network) Usually refers to a network in which some of the parts are connected using the public Internet, but the data sent across the Internet is encrypted, so the entire network is virtually private.
WAIS -- (Wide Area Information Servers) A commercial software package that
allows the indexing of huge quantities of information, and then making those indices
searchable across networks such as the Internet. A prominent feature of WAIS is that the
search results are ranked (scored) accordingto how relevant the hits are, and that
subsequent searches can find more stuff like that last batch and thus refine the search
Worm A worm is a virus that does not infect other programs. It
makes copies of itself, and infects additional computers (typically by making use of
network connections) but does not attach itself to additional programs; however a worm
might alter, install, or destroy files and programs.