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A
animated gif: A type of GIF
image that can be animated by combining several images into a single GIF file.
Applications that support the animated GIF standard, GIF89A, cycle
through each image. GIF animation doesn't give the same level of control and
flexibility as other animation formats but it has become extremely popular
because it is supported by nearly all Web browsers. In addition, animated GIF
files tend to be quite a bit smaller that other animation files, such as Java
applets.
ASCII: Acronym for the American Standard Code
for Information Interchange. Pronounced ask-ee, ASCII
is a code for representing English characters as numbers, with each letter
assigned a number from 0 to 127. For example, the ASCII code for uppercase M
is 77. Most computers use ASCII codes to represent text, which makes it possible
to transfer data from one computer to another.
ASP (Active Server Pages): A specification for a dynamically created
Web page with a .ASP extension that utilizes ActiveX scripting -- usually
VB Script or Jscript code. When a browser requests an ASP page, the Web server
generates a page with HTML code and sends it back to the browser. So ASP pages
are similar to CGI scripts, but they enable Visual Basic programmers to work
with familiar tools.
B
Binary: Pertaining to a number system that has just two unique digits.
For most purposes, we use the decimal number system, which has ten unique
digits, 0 through 9. All other numbers are then formed by combining these ten
digits. Computers are based on the binary numbering system, which consists of
just two unique numbers, 0 and 1.
Bookmarks: (v) To mark a document or a specific place in a document for
later retrieval. Nearly all Web browsers support a bookmarking feature that lets
you save the address (URL) of a Web page so that you can easily re-visit the
page at a later time.
(n) A marker or address that identifies a document or a specific place in a
document.
Browser: Short for Web browser, a software application used to
locate and display Web pages. The two most popular browsers are Netscape
Navigator and Microsoft Internet Explorer. Both of these are graphical
browsers, which means that they can display graphics as well as text. In
addition, most modern browsers can present multimedia information, including
sound and video, though they require plug-ins for some formats.
C
Cable modem: A modem designed to operate over cable TV
lines. Because the coaxial cable used by cable TV provides much greater
bandwidth than telephone lines, a cable modem can be used to achieve extremely
fast access to the World Wide Web. This, combined with the fact that millions of
homes are already wired for cable TV, has made the cable modem something of a
holy grail for Internet and cable TV companies.
CGI: Abbreviation of Common Gateway Interface,
a specification for transferring information between a World Wide Web server and
a CGI program. A CGI program is any program designed to accept and return data
that conforms to the CGI specification. The program could be written in any
programming language, including C, Perl, Java, or Visual Basic.
CGI programs are the most common way for Web servers to interact dynamically
with users. Many HTML pages that contain forms, for example, use a CGI program
to process the form's data once it's submitted.
Cookies: A message given to a Web browser by a Web server. The browser
stores the message in a text file called cookie.txt. The message is then
sent back to the server each time the browser requests a page from the server.
The main purpose of cookies is to identify users and possibly prepare
customized Web pages for them. When you enter a Web site using cookies, you may
be asked to fill out a form providing such information as your name and
interests. This information is packaged into a cookie and sent to your Web
browser which stores it for later use. The next time you go to the same Web
site, your browser will send the cookie to the Web server. The server can use
this information to present you with custom Web pages. So, for example, instead
of seeing just a generic welcome page you might see a welcome page with your
name on it.
D
DSL: Refers collectively to all types of digital subscriber
lines, the two main categories being ADSL and SDSL. Two other types
of xDSL technologies are High-data-rate DSL (HDSL) and Symmetric DSL (SDSL).
DSL technologies use sophisticated modulation schemes to pack data onto
copper wires. They are sometimes referred to as last-mile technologies because
they are used only for connections from a telephone switching station to a home
or office, not between switching stations.
E
Encryption: The translation of data into a secret code. Encryption is the
most effective way to achieve data security. To read an encrypted file, you must
have access to a secret key or password that enables you to decrypt it.
Unencrypted data is called plain text; encrypted data is referred to as cipher
text.
Ethernet: A local-area network (LAN) protocol developed by Xerox
Corporation in cooperation with DEC and Intel in 1976. Ethernet uses a bus or
star topology and supports data transfer rates of 10 Mbps. The Ethernet
specification served as the basis for the IEEE 802.3 standard, which specifies
the physical and lower software layers. Ethernet uses the CSMA/CD access method
to handle simultaneous demands. It is one of the most widely implemented LAN
standards.
A newer version of Ethernet, called 100Base-T (or Fast Ethernet),
supports data transfer rates of 100 Mbps. And the newest version, Gigabit
Ethernet supports data rates of 1 gigabit (1,000 megabits) per second.
F
Firewall: A system designed to prevent unauthorized access to or from a
private network. Firewalls can be implemented in both hardware and software, or
a combination of both. Firewalls are frequently used to prevent unauthorized
Internet users from accessing private networks connected to the Internet,
especially intranets. All messages entering or leaving the intranet pass through
the firewall, which examines each message and blocks those that do not meet the
specified security criteria.
A firewall is considered a first line of defense in protecting private
information. For greater security, data can be encrypted.
Forms: A formatted document containing blank fields that users can
fill in with data. With paper forms, it is usually necessary for someone to
transfer the data from the paper to a computer database, where the results can
then be statistically analyzed. They can't handle handwritten text. Electronic
forms solve this problem by entirely skipping the paper stage. Instead, the form
appears on the user's display screen and the user fills it in by selecting
options with a pointing device or typing in text from the computer keyboard. The
data is then sent directly to a forms processing application, which enters the
information into a database.
Frames: A feature supported by most modern Web browsers than enables
the Web author to divide the browser display area into two or more sections
(frames). The contents of each frame are taken from a different Web page. Frames
provide great flexibility in designing Web pages, but many designers avoid them
because they are supported unevenly by current browsers.
Freeware: Copyrighted software given away for free by the author.
Although it is available for free, the author retains the copyright, which means
that you cannot do anything with it that is not expressly allowed by the author.
Usually, the author allows people to use the software, but not sell it.
ftp: Abbreviation of File Transfer Protocol,
the protocol used on the Internet for sending files.
G
Gemini: Unix server available mostly for faculty and staff usage. User
is allotted 5MB of space.
.gif: Pronounced jiff or giff (hard g)
stands for graphics interchange format, a
bit-mapped graphics file format used by the World Wide Web, CompuServe and many
BBSs. GIF supports color and various resolutions. It also includes data
compression, making it especially effective for scanned photos. See also: animated
gif
H
HTML: Short for HyperText Markup Language,
the authoring language used to create documents on the World Wide Web.
HTTP: Short for HyperText Transfer Protocol,
the underlying protocol used by the World Wide Web. HTTP defines how messages
are formatted and transmitted, and what actions Web servers and browsers should
take in response to various commands. For example, when you enter a URL in your
browser, this actually sends an HTTP command to the Web server directing it to
fetch and transmit the requested Web page.
Hyperlink: An element in an electronic document that links to another
place in the same document or to an entirely different document. Typically, you
click on the hyperlink to follow the link. Hyperlinks are the most essential
ingredient of all hypertext systems, including the World Wide Web.
I
Internet: A global network connecting millions of computers. As of 1999,
the Internet has more than 200 million users worldwide, and that number is
growing rapidly. More than 100 countries are linked into exchanges of data, news
and opinions.
Unlike online services, which are centrally controlled, the Internet is
decentralized by design. Each Internet computer, called a host, is
independent. Its operators can choose which Internet services to use and which
local services to make available to the global Internet community.
Intranet: A network based on TCP/IP protocols (an internet) belonging
to an organization, usually a corporation, accessible only by the organization's
members, employees, or others with authorization. An intranet's Web sites look
and act just like any other Web sites, but the firewall surrounding an
intranet fends off unauthorized access.
ISP: Short for Internet Service Provider,
a company that provides access to the Internet. For a monthly fee, the service
provider gives you a software package, username, password and access phone
number. Equipped with a modem, you can then log on to the Internet and browse
the World Wide Web and USENET, and send and receive e-mail.
J
Javascript: A scripting language developed by Netscape to enable Web
authors to design interactive sites. Although it shares many of the features and
structures of the full Java language, it was developed independently. Javascript
can interact with HTML source code, enabling Web authors to spice up their sites
with dynamic content. JavaScript is endorsed by a number of software companies
and is an open language that anyone can use without purchasing a license. It is
supported by recent browsers from Netscape and Microsoft, though Internet
Explorer supports only a subset, which Microsoft calls Jscript.
.jpg: Short for Joint Photographic Experts
Group, and pronounced jay-peg. JPEG is a lossy compression
technique for color images. Although it can reduce files sizes to about 5% of
their normal size, some detail is lost in the compression.
K
L
M
Modem: Acronym for modulator-demodulator.
A modem is a device or program that enables a computer to transmit data over
telephone lines. Computer information is stored digitally, whereas information
transmitted over telephone lines is transmitted in the form of analog waves. A
modem converts between these two forms.
N
Network: A group of two or more computer systems linked together. There
are many types of computer networks, including:
- local-area networks (LANs) : The computers are geographically close
together (that is, in the same building).
- wide-area networks (WANs) : The computers are farther apart and are
connected by telephone lines or radio waves.
O
Opal: Windows NT server available for faculty and staff who wish to
publish FrontPage extensions.
Operating System: The most important program that
runs on a computer. Every general-purpose computer must have an operating system
to run other programs. Operating systems perform basic tasks, such as
recognizing input from the keyboard, sending output to the display screen,
keeping track of files and directories on the disk, and controlling peripheral
devices such as disk drives and printers.
For large systems, the operating system has even greater responsibilities and
powers. It is like a traffic cop -- it makes sure that different programs and
users running at the same time do not interfere with each other. The operating
system is also responsible for security, ensuring that unauthorized users do not
access the system.
Operating systems can be classified as follows:
- multi-user
: Allows two or more users to run programs at the
same time. Some operating systems permit hundreds or even thousands of
concurrent users.
- multiprocessing
: Supports running a program on more than one
CPU.
- multitasking
: Allows more than one program to run
concurrently.
- multithreading
: Allows different parts of a single program to
run concurrently.
- real time
real_time: Responds to input instantly.
General-purpose operating systems, such as DOS and UNIX, are not real-time.
Operating systems provide a software platform on top of which other programs,
called application programs, can run. The application programs must be
written to run on top of a particular operating system. Your choice of operating
system, therefore, determines to a great extent the applications you can run.
For PCs, the most popular operating systems are DOS, OS/2, and Windows, but
others are available, such as Linux.
As a user, you normally interact with the operating system through a set of
commands. For example, the DOS operating system contains commands such as COPY
and RENAME for copying files and changing the names of files, respectively. The
commands are accepted and executed by a part of the operating system called the
command processor or command line interpreter. Graphical user interfaces allow
you to enter commands by pointing and clicking at objects that appear on the
screen.
P
Packet: A piece of a message transmitted over a packet-switching
network. See under packet switching. One of the key
features of a packet is that it contains the destination address in addition to
the data. In IP networks, packets are often called datagrams.
Perl script: Short for Practical Extraction and Report Language,
Perl is a programming language developed by Larry Wall, especially designed for
processing text. Because of its strong text processing abilities, Perl has
become one of the most popular languages for writing CGI scripts. Perl is an
interpretive language, which makes it easy to build and test simple programs.
Q
R
S
Script: Another term for macro or batch file, a script is a list of
commands that can be executed without user interaction. A script language
is a simple programming language with which you can write scripts.
Server side Includes: Short for server-side include, a type of
HTML comment that directs the Web server to dynamically generate data for the
Web page whenever it is requested. The basic format for SSIs are:
<!--#command tag="value"…>
Where #command can be any of various commands supported by the Web server.
The simplest command is #include, which inserts the contents of another file.
This is especially useful for ensuring that boilerplate components, such as
headers and footers, are the same on all pages throughout a Web site. To change
a boilerplate element, you need only modify the include file, instead of
updating every individual Web page.
SSIs can also be used to execute programs and insert the results. They
therefore represent a powerful tool for Web developers.
There is no official standard for SSIs, so every Web server is free to
support different SSIs in different manners. However, many SSI commands, such as
#include and #exec, have become de facto standards.
Web pages that contain SSIs often end with a .shtml extension, though
this is not a requirement. The filename extension enables the Web server to
differentiate those pages that need to be processed before they are sent to the
browser.
Shareware: Software distributed on the basis of an honor system. Most
shareware is delivered free of charge, but the author usually requests that you
pay a small fee if you like the program and use it regularly. By sending the
small fee, you become registered with the producer so that you can receive
service assistance and updates. You can copy shareware and pass it along to
friends and colleagues, but they too are expected to pay a fee if they use the
product.
Shareware is inexpensive because it is usually produced by a single
programmer and is offered directly to customers. Thus, there are practically no
packaging or advertising expenses.
Note that shareware differs from public-domain software in that shareware is
copyrighted. This means that you cannot sell a shareware product as your own.
Spam: Electronic junk mail or junk newsgroup postings. Some people define
spam even more generally as any unsolicited e-mail. However, if a long-lost
brother finds your e-mail address and sends you a message, this could hardly be
called spam, even though it's unsolicited. Real spam is generally e-mail
advertising for some product sent to a mailing list or newsgroup.
In addition to wasting people's time with unwanted e-mail, spam also eats up
a lot of network bandwidth. Consequently, there are many organizations, as well
as individuals, who have taken it upon themselves to fight spam with a variety
of techniques. But because the Internet is public, there is really little that
can be done to prevent spam, just as it is impossible to prevent junk mail.
However, some private online services, such America Online, have instituted
policies to prevent spammers from spamming their subscribers.
There is some debate about the source of the term, but the generally accepted
version is that it comes from the Monty Python song, "Spam spam spam spam,
spam spam spam spam, lovely spam, wonderful spam…" Like the song, spam is
an endless repetition of worthless text. Another school of thought maintains
that it comes from the computer group lab at the University of Southern
California who gave it the name because it has many of the same characteristics
as the lunchmeat Spam:
- Nobody wants it or ever asks for it.
- No one ever eats it; it is the first item to be pushed to the side when
eating the entree.
- Sometimes it is actually tasty, like 1% of junk mail that is really useful
to some people.
T
T-1: A dedicated phone connection supporting
data rates of 1.544Mbits per second. A T-1 line actually consists of 24
individual channels, each of which supports 64Kbits per
second. Each 64Kbit/second channel can be configured to carry voice or data
traffic.
Trex2: VMS server used primarily by students
Tag: A command inserted in a document that specifies how the document,
or a portion of the document, should be formatted. Tags are used by all format
specifications that store documents as text files. This includes SGML and HTML.
U
Unix: Pronounced yoo-niks, a popular multi-user, multitasking
operating system developed at Bell Labs in the early 1970s. Created by just a
handful of programmers, UNIX was designed to be a small, flexible system used
exclusively by programmers. Although it has matured considerably over the years,
UNIX still betrays its origins by its cryptic command names and its general lack
of user-friendliness. This is changing, however, with graphical user interfaces
such as MOTIF.
UNIX was one of the first operating systems to be written in a high-level
programming language, namely C. This meant that it could installed on virtually
any computer for which a C compiler existed.
To date, there are two main dialects of UNIX; one produced by AT&T known
as System V and one developed at Berkeley University and known as BSD4.x, x
being a number from 1 to 3.
URL: Abbreviation of Uniform Resource Locator,
the global address of documents and other resources on the World Wide Web.
The first part of the address indicates what protocol to use, and the second
part specifies the IP address or the domain name where the resource is located.
V
VB (Visual Basic) script: A programming language and environment
developed by Microsoft. Based on the BASIC language, Visual Basic was one of the
first products to provide a graphical programming environment and a paint
metaphor for developing user interfaces. Instead of worrying about syntax
details, the Visual Basic programmer can add a substantial amount of code simply
by dragging and dropping controls, such as buttons and dialog boxes, and
then defining their appearance and behavior.
Although not a true object-oriented programming language in the strictest
sense, Visual Basic nevertheless has an object-oriented philosophy. It is
sometimes called an event-driven language because each object can react
to different events such as a mouse click.
Since its launch in 1990, the Visual Basic approach has become the norm for
programming languages. Now there are visual environments for many programming
languages, including C, C++, Pascal, and Java. Visual Basic is sometimes called
a Rapid Application Development (RAD) system because it enables programmers to
quickly build prototype applications.
VMS: Short for Virtual Memory System,
a multi-user, multitasking, virtual memory operating system that runs on DEC's
VAX and Alpha lines of minicomputers and workstations. VMS was introduced in
1979 along with the first VAX minicomputer.
W
WWW: The World Wide Web (WWW) is a system for organizing and
navigating information on the Internet. It utilizes Hypertext Transport Protocol
(HTTP) and the Hypertext Markup Language (HTML) to present text, graphics,
sound, and video as well as incorporating traditional Internet protocols like
gopher, FTP, WAIS, and telnet.
The mechanics are simple. A client program (commonly called a browser, eg
Netscape, Mosaic, Lynx) requests a WWW resource using an address called a
Uniform Resource Locator (URL). The URL specifies: 1. the protocol (http, FTP,
gopher, telnet), 2. the Web site where the resource is located, and 3. the full
directory path of the resource. In the URL:
http://www.montana.edu/~ousxx/netscape/net11.html
"http" is the protocol
www.montana.edu is the Web site
/~ousxx/netscape/net11.html is the full path
X
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