Internet is a vast network of computers that connects many of the world's businesses,
institutions, and individuals. The Internet, which means interconnected network of
networks, links tens of thousands of smaller computer networks. It enables computer
users throughout the world to send and receive messages, share information in a variety of
forms, and even play computer games with people thousands of miles away. Computers
linked to the Internet range from simple and inexpensive personal computers, often called
PC's, to huge mainframe computers used by government institutions, educational
institutions, and businesses.
Computers require special hardware and software to connect to the Internet. Necessary
hardware includes a modem, a device that translates a computer's digital information into
signals that can be transmitted over telephone lines (see MODEM). Required software
includes a communications program that allows the transmission and receipt of messages.
The Internet, often called simply the Net, began as a collection of text-based
information. But the development and rapid growth of a part of the Internet called
the World Wide Web (also known as WWW or the Web), transformed the presentation of
information on the Net. In addition to text, the Web allows the use of photographs,
moving pictures, and sound to create presentations approaching the visual quality of
television and the audio quality of recorded music.
Uses of the Internet
The major uses of the Internet include
communication, research, publishing, and sales.
Communication. Probably the most popular use of the Internet and the Web is
electronic mail, also called e-mail. Virtually every Internet user is assigned an
electronic address from which e-mail messages are sent and at which they are received.
The Internet carries hundreds of millions of e-mail messages each day.
An Internet service provider (ISP) offers local telephone numbers through which an
individual, using a computer and modem, can connect to the Internet. An ISP
maintains its customers' e-mail addresses, routes e-mail and requests for Internet-based
information to and from its users, and manages high-speed communications lines that speed
up Internet sessions. An on-line service provides a wide range of exclusive content
in addition to Internet access.
Research. The Internet is like a vast library, containing as much knowledge on
every subject as might be held in millions of books. Information is available in
many forms, from files consisting only of text to multimedia files that combine text,
photos, animation or video, software programs, and sound. Internet resources grow
larger every day.
Because of the ease with which information is stored on computers, and the speed with
which it can be accessed, the Internet is a popular first stop for many people performing
research. A businessperson might search Internet resources for help in developing
sales or product information. Students can access databases to find material related
to homework assignments or courses of study. Physicians use the Net to compare
medical treatments and to review advances in medical science. Scientists share
research data on the Internet.
Publishing. Publishers are increasingly using the Internet as a medium for
presenting newspapers, magazines, and books. Because information on the Net is
electronic, the publisher is freed from the costs of paper, printing, and distribution.
More importantly, the publisher can update information instantly, making it possible to
distribute far more current news than could be provided on paper.
Sales. Many businesses use the Internet to carry on commerce. Retail
establishments sell nearly every type of product over the Internet. Software
publishers view the Net as a convenient and inexpensive way to distribute products.
Over the Internet, users can buy new programs, sample programs before purchasing them, or
receive upgrades to programs they already own. Users generally make Internet
purchases with credit cards.
Because tens of millions of people use the Internet every day, advertisers are eager to
place messages in frequently visited spots. Those ads can be electronically linked
to an advertiser's own information, which often takes the form of elaborate multimedia
files. In effect, advertisers can invite Internet users to view commercials on
their computer. Additionally, a user can supply the advertiser with his or her
e-mail address to get further information or incentives, such as discount coupons.
The Internet also has important uses within the financial community. Many banks and
stockbrokers offer their customers software to make and track investments from their
Other uses. A popular feature of the Net is chat. Using special software,
users can gather in electronic "chat rooms" and send typed messages back and
forth, discussing topics of common interest. The Internet also features many
Web-based games with animation, sound effects, and music. Game players can challenge
players in distant countries to tournaments.
How the Internet works
Computer networks enable computers to
communicate and share information and resources. The simplest networks consist of a
user's computer, known as the client, and a resource computer, called the host or server
The client makes requests of the host, which, in turn, provides the requested resources,
such as information or software.
The Internet works in much the same way, on a far vaster scale. To connect to the
Net, a user logs on by instructing his or her computer's communication software to call
the Internet service provider. To protect the user's security, this process usually
requires a secret password.
Once connected to the ISP, the user has several options. For some functions, such as
e-mail or text-only resources known as newsgroups, the user's communications software
alone may provide access. Most such software includes simple word processors in
which messages can be composed or read.
For more sophisticated resources, such as the World Wide Web, an additional piece of
software known as a browser is used. With a browser running, a computer user may
access millions of sites around the world. Each site has a separate electronic
address, known as a uniform resource locator (URL). Directories of these addresses
are maintained and constantly updated throughout the Internet. The addresses
themselves are organized into various domains (categories), such as educational,
commercial, or organizations. In a URL, the domain type takes the form of a
three-letter extension, such as . edu for education and . com for commercial.
By typing an address, or by clicking the computer mouse's cursor on a picture or word
linked electronically to the address, the user transmits a request through the ISP and
onto the larger Internet. When the request arrives at the desired destination, the
server computer responds by sending the user its information. This information often
takes the form of a starting page called a home page, which is similar to the table of
contents of a book or magazine. From a home page, the user can search for further
information by using links to other pages within the same Web site or to other Web sites.
Because there are tens of millions of sites, most browsers include systems for bookmarking
(recording) the addresses of favorite or frequently visited sites. Once a site has
been bookmarked, the user need simply click on the appropriate bookmark to visit the site
A user need not know in advance the address of the desired information. Among the
most popular features of the Internet and World Wide Web are search engines. These
programs offer users the opportunity to type in key words or phrases related to the
information they seek. The search engine then reviews indexes of information and
sites on the Internet and the Web, providing the user with the addresses of sites that
most closely match the request. Because search engine sites are used frequently by
millions of people, they are popular spotsfor advertisements.
The Internet and society
The Internet has made huge amounts of
information accessible to more people than ever before. The development of the Web
in the early 1990's made the Internet relatively easy and fun to use by adding graphics,
motion, and sound and by using pictures to represent computer commands. This
accessibility has raised some serious questions.
Among these questions are doubts about the appropriateness of information. Not all
of the information on the Internet and the Web is accurate, and some is deliberately
misleading. Many schools teach students how to evaluate information derived from
Many parents worry about violent or pornographic material available on the Net.
Criminals may lurk in chat rooms, seeking to arrange face-to-face meetings with
unsuspecting victims. Special programs known as parental control software can help
parents restrict access to sites that may be unsuitable for children.
The Internet also poses security concerns. Mischievous programmers known as hackers
often try to break into large computer systems. Some hackers damage databases stored
in these systems or attempt to steal information or electronic funds. Others may
seek access to credit card numbers and other individual financial information. Many
people are concerned about the security and confidentiality of credit card numbers used to
make purchases over the Internet.
Software itself can become a danger on the Internet. Programs known as viruses,
e-mail bombs, or Trojan horses have been distributed across the Internet and can cause
damage to data on systems that receive them. Many companies produce software
designed to protect users against unwanted and damaging viruses.
Most people believe that the benefits of the Internet far outweigh its dangers.
Although the Internet and the Web have grown quickly, they have revealed only a fraction
of their potential as tools for education, research, communication, news, and
History of the Internet
The Internet began to take shape in the late
1960's. The United States Department of Defense was concerned at the time about the
possibility of devastating nuclear warfare. It began investigating means of linking
various computer installations together so that their ability to communicate might
withstand a war. Through its Advanced Research Projects Agency (ARPA), the Defense
Department initiated ARPANet, a network of university and military computers.
The network's operating protocols (rules) laid the groundwork for relatively fast and
error-free computer-to-computer communication. Other networks adopted these
protocols, which in turn evolved as new computer and communications technologies became
Throughout the 1970's, the ARPANet grew at a slow but steady pace. Computers in
other countries began to join the network. Other networks came into existence as
well. These included Unix to Unix Copy (UUCP), which was established to serve users
of the UNIX computer programming language, and the User's Network (USENET), a medium for
posting text-based articles on a variety of subjects.
By 1981, just over 200 computers were connected to ARPANet. The U.S. military then
divided the network into two organizations--ARPANet and a purely military network.
During the 1980's, ARPANet was absorbed by NSFNET, a more advanced network developed by
the National Science Foundation. Soon, the collection of networks became known
simply as the Internet.
One of the reasons for the slow growth of the early Internet was the difficulty of using
the network. To access its information, users had to master complex series of
programming commands that required either memorization or frequent reference to special
The Internet's breakthrough to mass popularity occurred in 1991 with the arrival of the
World Wide Web. The Web was developed by Tim Berners-Lee, a British computer
scientist at the European Center for Nuclear Research (CERN). This development
opened the Internet to multimedia.
In addition, the programming language that the Web used, called HyperText Markup Language
(HTML), made it far easier to link information from computers throughout the world.
This development effectively created an interactive index that enabled users to jump
easily from the resources of one computer to another, effortlessly following an
information trail around the world.
The arrival of browsers in 1993 further simplified use of the Web and the Internet, and
brought about staggering growth in the Internet. Today, there are tens of millions
of computer users accessing the Net and the Web daily. As the Internet incorporates
new technologies that add such features as spoken-word commands, instantaneous
translation, and increased availability of historical and archival material, it will
continue its rapid growth.
Glossary of Internet terms
Bulletin board is an electronic message center. Most bulletin boards serve specific
interest groups. They allow users to read messages left by others and to leave their own
Chat room is a location on the Internet where users can discuss topics of common interest
by sending typed messages back and forth. The messages appear to other users as soon as
they are typed.
Client is a user's computer.
Cookie is a piece of data placed on a client's hard drive by a server. It can be used for
a variety of purposes. One such purpose would be to store a name and password so that a
user would not have to enter this information every time he or she returned to the same
Download is to receive data or software over the Internet and store it so that it may be
E-mail , or electronic mail, is a way of sending a message over the Internet to another
specific user or group of users.
Firewall is a combination of hardware and software that prevents a visitor to an
organization's Web site from gaining access to other information stored on the
organization's computer network, such as corporate records or employee information.
Forum , or newsgroup, is an on-line discussion group in which participants with a common
interest can exchange open messages.
Home page is the starting page of a Web site. It generally includes tools and indexes to
help visitors navigate through the rest of the site. In many ways, a home page functions
as an electronic table of contents.
Hyperlink is a programmed connection from one Web site to another. It usually appears on a
Web site as a highlighted or underlined word or phrase. When a user clicks a mouse on the
passage, the client connects to the related Web site.
Hypertext markup language , or HTML, is the programming language most commonly used by the
World Wide Web.
Hypertext transfer protocol , or HTTP, is the set of rules governing the transfer of files
between a server and a client. HTTP electronically oversees the connection of clients to
Internet service provider is a business that provides a client with the means to connect
to the Internet and maintains exchanges of information between clients and servers.
Modem is a device that converts a computer's digital information to signals that can be
transmitted over telephone lines. It also converts signals it receives back to digital
Net is a common abbreviation for Internet.
Network is a communication system that links two or more computers.
On-line service is a business that provides Internet access plus a wide range of exclusive
content and features, such as chat rooms, games, and news reports.
Search engine is a program that allows a user to locate information on the Internet by
typing in key words or phrases. The search engine then returns addresses of Web sites that
most closely match the request.
Server , or host, is a computer that provides requested resources, such as information or
software, to a client via a modem or network connection.
Surfing is the process of visiting a number of Web sites in rapid succession.
Uniform resource locator, or URL, is an electronic address that identifies a Web site.
Web browser , or simply browser, is a piece of software that allows a user to access Web
Web site is a collection of information at a specific address on the World Wide Web.
World Wide Web , or WWW for short, is a part of the Internet that includes text, graphics,
video, animation, and sound.