Internet Term Glossary - A to G
-A-
ADSL -
(Asymmetric Digital Subscriber Line)
ADSL line where the upload speed is different from the download speed. Usually
the download speed is much greater.
Applet
A
small Java program that can be embedded in an HTML page. Applets differ from
full-fledged Java applications in that they are not allowed to access certain
resources on the local computer, such as files and serial devices (modems,
printers, etc.), and are prohibited from communicating with most other
computers across a network. The common rule is that an applet can only make an
Internet connection to the computer from which the applet was sent.
Application
Server
Server
software that manages one or more other pieces of software in a way that makes
the managed software available over a network, usually to a Web server. By
having a piece of software manage other software packages it is possible to use
resources like memory and database access more efficiently than if each of the
managed packages responded directly to requests.
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.
Backbone
A
high-speed line or series of connections that forms a major pathway within a
network. The term is relative as a backbone in a small network will likely be
much smaller than many non-backbone lines in a large network.
Bandwidth
How
much stuff you can send through a connection. Usually measured in
bits-per-second. A full page of English text is about 16,000 bits. A fast modem
can move about 57,000 bits in one second. Full-motion full-screen video would
require roughly 10,000,000 bits-per-second, depending on compression.
Binary
Information
consisting entirely of ones and zeros. Also, commonly used to refer to files
that are not simply text files, e.g. images.
Binhex
- (BINary HEXadecimal)
A
method for converting non-text files (non-ASCII) into ASCII. This is needed
because Internet email can only handle ASCII.
Bit - (Binary DigIT)
A
single digit number in base-2, in other words, either a 1 or a zero. The
smallest unit of computerized data. Bandwidthis usually measured in
bits-per-second.
BITNET - (Because It's Time NETwork (or
Because It's There NETwork))
A
network of educational sites separate from the Internet, but email is freely
exchanged between BITNET and the Internet. Listservs®, a popular form of email
discussion groups, originated on BITNET. At its peak (the late 1980's and early
1990's) BITNET machines were usually mainframes, often running IBM's MVS
operating system. BITNET is probably the only international network that is
shrinking.
Bps - (Bits-Per-Second)
A
measurement of how fast data is moved from one place to another. A 56K modem
can move about 57,000 bits per second.
Browser
A
Client program (software) that is used to look at various kinds of Internet
resources.
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.
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 (the ?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 CGIprograms 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. EachClient 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.
Cookie
The
most common meaning of "Cookie" on the Internet refers to a piece of
information sent by a Web Server to a Web Browser that the Browser software is
expected to save and to send back to the Server whenever the browser makes
additional requests from the Server.
Depending
on the type of Cookie used, and the Browsers' settings, the Browser may accept
or not accept the Cookie, and may save the Cookie for either a short time or a
long time.
Cookies
might contain information such as login or registration information, online
"shopping cart" information, user preferences, etc.
When
a Server receives a request from a Browser that includes a Cookie, the Server
is able to use the information stored in the Cookie. For example, the Server
might customize what is sent back to the user, or keep a log of particular
users' requests.
Cookies
are usually set to expire after a predetermined amount of time and are usually
saved in memory until the Browser software is closed down, at which time they
may be saved to disk if their "expire time" has not been reached.
Cookies
do not read your hard drive and send your life story to the CIA, but they can
be used to gather more information about a user than would be possible without
them.
CSS - (Cascading Style Sheet)
A
standard for specifying the appearance of text and other elements. CSS was
developed for use with HTML in Web pages but is also used in other situations,
notably in applications built using XPFE. CSS is typically used to provide a
single "library" of styles that are used over and over throughout a
large number of related documents, as in a web site. A CSS file might specify
that all numbered lists are to appear in italics. By changing that single
specification the look of a large number of documents can be easily changed.
DNS - (Domain Name System)
The
Domain Name System is the system that translates Internet domain names into IP
numbers. A "DNS Server" is a server that performs this kind of
translation.
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:
netzetera.lu
mail.netzetera.lu
workshop.netzetera.lu
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 (netzetera.lu 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 email 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.
Download
Transferring
data (usually a file) from a another computer to the computer you are are
using. The opposite of upload.
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 Subscriber Line.
Another
common configuration is symmetrical: 384 Kilobits per second in both
directions.
In
theory ADSL allows download speeds of up to 9 megabits per second and upload
speeds of up to 640 kilobits per second.
DSL
is now a popular alternative to Leased Lines and ISDN, being faster than ISDN
and less costly than traditional Leased Lines.
Email - (Electronic Mail)
Messages,
usually text, sent from one person to another via computer. Email can also be
sent automatically to a large number of addresses.
Ethernet
A
very common method of networking computers in a LAN.
There
is more than one type of Ethernet. By 2001 the standard type was
"100-BaseT" which can handle up to about 100,000,000 bits-per-second
and can be used with almost any kind of computer.
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.)
FAQ - (Frequently Asked Questions)
FAQs
are documents that list and answerthe most common questions on a particular
subject. There are hundreds of FAQs on subjects as diverse as Pet Grooming and
Cryptography. FAQs are usually written by people who have tired of answering
the same question over and over.
Finger
An
Internet software tool for locating people on other Internet sites. Finger is
also sometimes used to give access to non-personal information, but the most
common use is to see if a person has an account at a particular Internet site.
Many sites do not allow incoming Finger requests, but many do.
Fire
Wall
A
combination of hardware and software that separates a Network into two or more
parts for security purposes.
FTP - (File Transfer Protocol)
A
very common method of moving files between two Internet sites.
FTP
is a way to login to another Internet site for the purposes of retrieving
and/or sending files. There are many Internet sites that have established
publicly accessible repositories of material that can be obtained using FTP, by
logging in using the account name "anonymous", thus these sites are
called "anonymous ftp servers".
FTP
was invented and in wide use long before the advent of the World Wide Web and
originally was always used from a text-only interface.
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 email format and Internet email 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.
GIF - (Graphic Interchange Format)
A
common format for image files, especially suitable for images containing large
areas of the same color. GIF format files of simple images are often smaller
than the same file would be if stored in JPEG format, but GIF format does not
store photographic images as well as JPEG.
Gigabyte
1000
or 1024 Megabytes, depending on who is measuring.
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