Internet
Electronic Newspaper
In the late 1990s newspapers began
offering their content on the Internet in record numbers. By the end of the
decade, more than 1,000 North American newspapers offered online versions, most
available to Internet users free of charge. Electronic newspapers spared
publishers one of their highest expenses—newsprint—and many brought publishers
additional advertising revenue. The New York Times on the Web, an exerpt of
which is shown here, offers readers the same content as its print publication
as well as stories and features available only in its online version.
Internet, computer-based global
information system. The Internet is composed of many interconnected computer
networks. Each network may link tens, hundreds, or even thousands of computers,
enabling them to share information and processing power. The Internet has made
it possible for people all over the world to communicate with one another
effectively and inexpensively. Unlike traditional broadcasting media, such as
radio and television, the Internet does not have a centralized distribution
system. Instead, an individual who has Internet access can communicate directly
with anyone else on the Internet, post information for general consumption,
retrieve information, use distant applications and services, or buy and sell
products.
The Internet has brought
new opportunities to government, business, and education. Governments use the
Internet for internal communication, distribution of information, and automated
tax processing. In addition to offering goods and services online to customers,
businesses use the Internet to interact with other businesses. Many individuals
use the Internet for communicating through electronic mail (e-mail), retrieving
news, researching information, shopping, paying bills, banking, listening to
music, watching movies, playing games, and even making telephone calls.
Educational institutions use the Internet for research and to deliver online
courses and course material to students.
Use of the Internet has
grown tremendously since its inception. The Internet’s success arises from its
flexibility. Instead of restricting component networks to a particular
manufacturer or particular type, Internet technology allows interconnection of
any kind of computer network. No network is too large or too small, too fast or
too slow to be interconnected. Thus, the Internet includes inexpensive networks
that can only connect a few computers within a single room as well as expensive
networks that can span a continent and connect thousands of computers. See Local
Area Network.
Internet service providers
(ISPs) provide Internet access to customers, usually for a monthly fee. A
customer who subscribes to an ISP’s service uses the ISP’s network to access
the Internet. Because ISPs offer their services to the general public, the
networks they operate are known as public access networks. In the United
States, as in many countries, ISPs are private companies; in countries where
telephone service is a government-regulated monopoly, the government often
controls ISPs.
An organization that has
many computers usually owns and operates a private network, called an intranet,
which connects all the computers within the organization. To provide Internet
service, the organization connects its intranet to the Internet. Unlike public
access networks, intranets are restricted to provide security. Only authorized
computers at the organization can connect to the intranet, and the organization
restricts communication between the intranet and the global Internet. The
restrictions allow computers inside the organization to exchange information
but keep the information confidential and protected from outsiders.
The Internet has doubled in
size every 9 to 14 months since it began in the late 1970s. In 1981 only 213
computers were connected to the Internet. By 2000 the number had grown to more
than 400 million. The current number of people who use the Internet can only be
estimated. Some analysts said that the number of users was expected to top 1
billion by the end of 2005.
II
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USES OF THE INTERNET
|
Marketing and the Internet
The Internet enables marketers to
promote products and services to millions of potential customers through the
World Wide Web. This Web site provides information about a product designed to
keep vegetables fresh.
Before the Internet was
created, the U.S. military had developed and deployed communications networks,
including a network known as ARPANET. Uses of the networks were restricted to
military personnel and the researchers who developed the technology. Many
people regard the ARPANET as the precursor of the Internet. From the 1970s
until the late 1980s the Internet was a U.S. government-funded communication
and research tool restricted almost exclusively to academic and military uses.
It was administered by the National Science Foundation (NSF). At universities,
only a handful of researchers working on Internet research had access. In the
1980s the NSF developed an “acceptable use policy” that relaxed restrictions
and allowed faculty at universities to use the Internet for research and
scholarly activities. However, the NSF policy prohibited all commercial uses of
the Internet. Under this policy advertising did not appear on the Internet, and
people could not charge for access to Internet content or sell products or
services on the Internet.
By 1995, however, the NSF
ceased its administration of the Internet. The Internet was privatized, and
commercial use was permitted. This move coincided with the growth in popularity
of the World Wide Web (WWW), which was developed by British physicist and computer
scientist Timothy Berners-Lee. The Web replaced file transfer as the
application used for most Internet traffic. The difference between the Internet
and the Web is similar to the distinction between a highway system and a
package delivery service that uses the highways to move cargo from one city to
another: The Internet is the highway system over which Web traffic and traffic
from other applications move. The Web consists of programs running on many
computers that allow a user to find and display multimedia documents (documents
that contain a combination of text, photographs, graphics, audio, and video).
Many analysts attribute the explosion in use and popularity of the Internet to
the visual nature of Web documents. By the end of 2000, Web traffic dominated the
Internet—more than 80 percent of all traffic on the Internet came from the Web.
Companies, individuals, and
institutions use the Internet in many ways. Companies use the Internet for
electronic commerce, also called e-commerce, including advertising, selling,
buying, distributing products, and providing customer service. In addition,
companies use the Internet for business-to-business transactions, such as
exchanging financial information and accessing complex databases. Businesses
and institutions use the Internet for voice and video conferencing and other
forms of communication that enable people to telecommute (work away from
the office using a computer). The use of e-mail speeds communication between
companies, among coworkers, and among other individuals. Media and
entertainment companies run online news and weather services over the Internet,
distribute music and movies, and actually broadcast audio and video, including
live radio and television programs. File sharing services let individuals swap
music, movies, photos, and applications, provided they do not violate copyright
protections. Online chat allows people to carry on discussions using written
text. Instant messaging enables people to exchange text messages; share digital
photo, video, and audio files; and play games in real time. Scientists and
scholars use the Internet to communicate with colleagues, perform research,
distribute lecture notes and course materials to students, and publish papers
and articles. Individuals use the Internet for communication, entertainment,
finding information, and buying and selling goods and services.
III
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HOW THE INTERNET WORKS
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A
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Internet Access
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The term Internet access
refers to the communication between a residence or a business and an ISP
that connects to the Internet. Access falls into three broad categories:
dedicated, dial-up, and wireless. With dedicated access, a subscriber’s
computer remains directly connected to the Internet at all times through a
permanent, physical connection. Most large businesses have high-capacity
dedicated connections; small businesses or individuals that desire dedicated
access choose technologies such as digital subscriber line (DSL) or cable modems,
which both use existing wiring to lower cost. A DSL sends data across the same
wires that telephone service uses, and cable modems use the same wiring that
cable television uses. In each case, the electronic devices that are used to
send data over the wires employ separate frequencies or channels that do not
interfere with other signals on the wires. Thus, a DSL Internet connection can
send data over a pair of wires at the same time the wires are being used for a
telephone call, and cable modems can send data over a cable at the same time
the cable is being used to receive television signals. Another, less-popular
option is satellite Internet access, in which a computer grabs an Internet
signal from orbiting satellites via an outdoor satellite dish. The user usually
pays a fixed monthly fee for a dedicated connection. In exchange, the company
providing the connection agrees to relay data between the user’s computer and
the Internet.
Dial-up is the least expensive
access technology, but it is also the least convenient. To use dial-up access,
a subscriber must have a telephone modem, a device that connects a computer to
the telephone system and is capable of converting data into sounds and sounds
back into data. The user’s ISP provides software that controls the modem. To
access the Internet, the user opens the software application, which causes the
dial-up modem to place a telephone call to the ISP. A modem at the ISP answers
the call, and the two modems use audible tones to send data in both directions.
When one of the modems is given data to send, the modem converts the data from
the digital values used by computers—numbers stored as a sequence of 1s and
0s—into tones. The receiving side converts the tones back into digital values.
Unlike dedicated access technologies, a dial-up modem does not use separate
frequencies, so the telephone line cannot be used for regular telephone calls
at the same time a dial-up modem is sending data.
B
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How Information Travels Over the
Internet
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Internet Topology
Connecting individual computers to each
other creates networks. The Internet is a series of interconnected networks.
Personal computers and workstations are connected to a Local Area Network (LAN)
by either a dial-up connection through a modem and standard phone line or by
being directly wired into the LAN. Other modes of data transmission that allow
for connection to a network include T-1 connections and dedicated lines.
Bridges and hubs link multiple networks to each other. Routers transmit data
through networks and determine the best path of transmission.
All information is transmitted
across the Internet in small units of data called packets. Software on the sending
computer divides a large document into many packets for transmission; software
on the receiving computer regroups incoming packets into the original document.
Similar to a postcard, each packet has two parts: a packet header specifying
the computer to which the packet should be delivered, and a packet payload
containing the data being sent. The header also specifies how the data in the
packet should be combined with the data in other packets by recording which
piece of a document is contained in the packet.
A series of rules known
as computer communication protocols specify how packet headers are formed and
how packets are processed. The set of protocols used for the Internet is named
TCP/IP after the two most important protocols in the set: the Transmission
Control Protocol and the Internet Protocol. TCP/IP protocols enable the
Internet to automatically detect and correct transmission problems. For
example, if any network or device malfunctions, protocols detect the failure
and automatically find an alternative path for packets in order to avoid the
malfunction. Protocol software also ensures that data arrives complete and
intact. If any packets are missing or damaged, protocol software on the
receiving computer requests that the source resend them. Only when the data has
arrived correctly does the protocol software make it available to the receiving
application program, and therefore to the user.
Hardware devices that connect
networks in the Internet are called IP routers because they follow the IP protocol
when forwarding packets. A router examines the header in each packet that
arrives to determine the packet’s destination. The router either delivers the
packet to the destination computer across a local network or forwards the
packet to another router that is closer to the final destination. Thus, a
packet travels from router to router as it passes through the Internet. In some
cases, a router can deliver packets across a local area wireless network,
allowing desktop and laptop computers to access the Internet without the use of
cables or wires. Today’s business and home wireless local area networks (LANs),
which operate according to a family of wireless protocols known as Wi-Fi, are
fast enough to deliver Internet feeds as quickly as wired LANs.
Increasingly, cell phone
and handheld computer users are also accessing the Internet through wireless
cellular telephone networks. Such wide area wireless access is much slower than
high-capacity dedicated, or broadband, access, or dial-up access. Also, handheld
devices, equipped with much smaller screens and displays, are more difficult to
use than full-sized computers. But with wide area wireless, users can access
the Internet on the go and in places where access is otherwise impossible.
Telephone companies are currently developing so-called 3G—for “third
generation”—cellular networks that will provide wide area Internet access at
DSL-like speeds. See also Wireless Communications.
C
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Network Names and Addresses
|
To be connected to the
Internet, a computer must be assigned a unique number, known as its IP
(Internet Protocol) address. Each packet sent over the Internet contains the IP
address of the computer to which it is being sent. Intermediate routers use the
address to determine how to forward the packet. Users almost never need to
enter or view IP addresses directly. Instead, to make it easier for users, each
computer is also assigned a domain name; protocol software automatically
translates domain names into IP addresses. See also Domain Name System.
Users encounter domain names
when they use applications such as the World Wide Web. Each page of information
on the Web is assigned a URL (Uniform Resource Locator) that includes the
domain name of the computer on which the page is located. Other items in the
URL give further details about the page. For example, the string http
specifies that a browser should use the http protocol, one of many TCP/IP
protocols, to fetch the item.
D
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Client/Server Architecture
|
Internet applications, such as the
Web, are based on the concept of client/server architecture. In a client/server
architecture, some application programs act as information providers (servers),
while other application programs act as information receivers (clients). The
client/server architecture is not one-to-one. That is, a single client can
access many different servers, and a single server can be accessed by a number
of different clients. Usually, a user runs a client application, such as a Web
browser, that contacts one server at a time to obtain information. Because it
only needs to access one server at a time, client software can run on almost
any computer, including small handheld devices such as personal organizers and
cellular telephones. To supply information to others, a computer must run a
server application. Although server software can run on any computer, most
companies choose large, powerful computers to run server software because the
company expects many clients to be in contact with its server at any given
time. A faster computer enables the server program to return information with
less delay.
E
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Electronic Mail
|
Electronic mail, or e-mail,
is a widely used Internet application that enables individuals or groups of
individuals to quickly exchange messages, even if they are separated by long
distances. A user creates an e-mail message and specifies a recipient using an
e-mail address, which is a string consisting of the recipient’s login name
followed by an @ (at) sign and then a domain name. E-mail software transfers
the message across the Internet to the recipient’s computer, where it is placed
in the specified mailbox, a file on the hard drive. The recipient uses an
e-mail application to view and reply to the message, as well as to save or
delete it. Because e-mail is a convenient and inexpensive form of
communication, it has dramatically improved personal and business
communications.
In its original form,
e-mail could only be sent to recipients named by the sender, and only text messages
could be sent. E-mail has been extended in two ways, and is now a much more
powerful tool. Software has been invented that can automatically propagate to
multiple recipients a message sent to a single address. Known as a mail gateway
or list server, such software allows individuals to join or leave a mail list
at any time. Such software can be used to create lists of individuals who will
receive announcements about a product or service or to create online discussion
groups.
E-mail software has also
been extended to allow the transfer of nontext documents, such as photographs
and other images, executable computer programs, and prerecorded audio. Such
documents, appended to an e-mail message, are called attachments. The standard
used for encoding attachments is known as Multipurpose Internet Mail Extensions
(MIME). Because the Internet e-mail system only transfers printable text, MIME
software encodes each document using printable letters and digits before
sending it and then decodes the item when e-mail arrives. Most significantly,
MIME allows a single message to contain multiple items, enabling a sender to
include a cover letter that explains each of the attachments.
F
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Other Internet Applications
|
Although the World Wide Web
is the most popular application, some older Internet applications are still
used. For example, the Telnet application enables a user to interactively
access a remote computer. Telnet gives the appearance that the user’s keyboard
and monitor are connected directly to the remote computer. For example, a
businessperson who is visiting a location that has Internet access can use
Telnet to contact their office computer. Doing so is faster and less expensive
than using a dial-up modem.
Another application, known as
the File Transfer Protocol (FTP), is used to download files from an Internet
site to a user’s computer. The FTP application is often automatically invoked
when a user downloads an updated version of a piece of software. Applications
such as FTP have been integrated with the World Wide Web, making them
transparent so that they run automatically without requiring users to open
them. When a Web browser encounters a URL that begins with ftp:// it
automatically uses FTP to access the item.
Network News discussion groups (newsgroups),
originally part of the Usenet network, are another form of online discussion.
Thousands of newsgroups exist, on an extremely wide range of subjects. Messages
to a newsgroup are not sent directly to each user. Instead, an ordered list is
disseminated to computers around the world that run news server software.
Newsgroup application software allows a user to obtain a copy of selected
articles from a local news server or to use e-mail to post a new message to the
newsgroup. The system makes newsgroup discussions available worldwide.
A service known as Voice
Over IP (VoIP) allows individuals and businesses to make phone calls over the
Internet. Low-cost services (some of them free) often transfer calls via
personal computers (PCs) equipped with microphones and speakers instead of the
traditional telephone handset. But a growing number of services operate outside
the PC, making calls via a special adapter that connects to a traditional
telephone handset. The calls still travel over the Internet, but the person
using the special adapter never has to turn on his or her computer. Thousands
now use such VoIP services in lieu of traditional phone service. VoIP services
are not subject to the same government regulation as traditional phone service.
Thus, they are often less expensive.
G
|
Bandwidth
|
Computers store all information
as binary numbers. The binary number system uses two binary digits, 0 and 1,
which are called bits. The amount of data that a computer network can transfer
in a certain amount of time is called the bandwidth of the network and is
measured in kilobits per second (kbps) or megabits per second (mbps). A kilobit
is 1 thousand bits; a megabit is 1 million bits. A dial-up telephone modem can
transfer data at rates up to 56 kbps; DSL and cable modem connections are much
faster and can transfer at a few mbps. The Internet connections used by
businesses can operate at 45 mbps or more, and connections between routers in
the heart of the Internet may operate at rates from 2,488 to 9,953 mbps (9.953
gigabits per second). The terms wideband or broadband are used to
characterize networks with high capacity, such as DSL and cable, and to
distinguish them from narrowband networks, such as dial-up modems, which have
low capacity.
IV
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HISTORY
|
Timothy Berners-Lee
Timothy Berners-Lee, a British computer
scientist, developed the World Wide Web during the 1980s.
Research on dividing information
into packets and switching them from computer to computer began in the 1960s.
The U.S. Department of Defense Advanced Research Projects Agency (ARPA) funded
a research project that created a packet switching network known as the
ARPANET. ARPA also funded research projects that produced two satellite
networks. In the 1970s ARPA was faced with a dilemma: Each of its networks had
advantages for some situations, but each network was incompatible with the
others. ARPA focused research on ways that networks could be interconnected,
and the Internet was envisioned and created to be an interconnection of
networks that use TCP/IP protocols. In the early 1980s a group of academic
computer scientists formed the Computer Science NETwork, which used TCP/IP
protocols. Other government agencies extended the role of TCP/IP by applying it
to their networks: The Department of Energy’s Magnetic Fusion Energy Network
(MFENet), the High Energy Physics NETwork (HEPNET), and the National Science
Foundation NETwork (NSFNET).
In the 1980s, as large
commercial companies began to use TCP/IP to build private internets, ARPA
investigated transmission of multimedia—audio, video, and graphics—across the
Internet. Other groups investigated hypertext and created tools such as Gopher
that allowed users to browse menus, which are lists of possible options. In
1989 many of these technologies were combined to create the World Wide Web.
Initially designed to aid communication among physicists who worked in widely
separated locations, the Web became immensely popular and eventually replaced
other tools. Also during the late 1980s, the U.S. government began to lift
restrictions on who could use the Internet, and commercialization of the
Internet began. In the early 1990s, with users no longer restricted to the
scientific or military communities, the Internet quickly expanded to include universities,
companies of all sizes, libraries, public and private schools, local and state
governments, individuals, and families.
V
|
THE FUTURE OF THE INTERNET
|
Several technical challenges
must be overcome if the Internet is to continue growing at the current
phenomenal rate. The primary challenge is to create enough capacity to
accommodate increases in traffic. Internet traffic is increasing as more people
become Internet users and existing users send greater amounts of data. If the
volume of traffic increases faster than the capacity of the network increases,
congestion will occur, similar to the congestion that occurs when too many cars
attempt to use a highway. To avoid congestion, researchers have developed
technologies, such as Dense Wave Division Multiplexing (DWDM), that transfer
more bits per second across an optical fiber. The speed of routers and other
packet-handling equipment must also increase to accommodate growth. In the
short term, researchers are developing faster electronic processors; in the
long term, new technologies will be required.
Another challenge involves IP
addresses. Although the original protocol design provided addresses for up to
4.29 billion individual computers, the addresses have begun to run out because
they were assigned in blocks. Researchers developed technologies, such as
Network Address Translation (NAT), to conserve addresses. NAT allows multiple
computers at a residence to “share” a single Internet address. Engineers have
also planned a next-generation of IP, called IPv6, which will handle many more
addresses than the current version.
Short, easy-to-remember domain names
were once in short supply. Many domain names that used the simple format
http://www.[word].com, where [word] is a common noun or verb, and .com referred
to a for-profit business were mostly taken by 2001. Until 2001, only a few
endings were allowed, such as .com, .org, and .net. By 2002, however,
additional endings began to be used, such as .biz for businesses and .info for
informational sites. This greatly expanded the number of possible URLs.
Other important questions
concerning Internet growth relate to government controls, especially taxation
and censorship. Because the Internet has grown so rapidly, governments have had
little time to pass laws that control its deployment and use, impose taxes on
Internet commerce, or otherwise regulate content. Many Internet users in the
United States view censorship laws as an infringement on their constitutional right
to free speech. In 1996 the Congress of the United States passed the
Communications Decency Act, which made it a crime to transmit indecent material
over the Internet. The act resulted in an immediate outcry from users, industry
experts, and civil liberties groups opposed to such censorship. In 1997 the
Supreme Court of the United States declared the act unconstitutional because it
violated First Amendment rights to free speech. The U.S. Congress responded in
1998 by passing a narrower antipornography bill, the Child Online Protection
Act (COPA). COPA required commercial Web sites to ensure that children could
not access material deemed harmful to minors. In 1999 a federal judge blocked
COPA as well, ruling that it would dangerously restrict constitutionally
protected free speech. The judge’s ruling was upheld by a federal appeals court
on the grounds that the law’s use of “community standards” in deciding what was
pornographic was overly broad.
The issue reached the
Supreme Court of the United States in 2002, and in a limited ruling the Supreme
Court found that the community standard provision was not inherently
unconstitutional. Supporters of the law welcomed the Court’s ruling. However,
opponents noted that the Court had sent the case back to the federal appeals
court for a more comprehensive review and had ruled that the law could not go
into effect until that review occurred. Some analysts who studied the various
opinions written by the justices concluded that a majority of the Court was
likely to find the law unconstitutional.
Increasing commercial use of the
Internet has heightened security and privacy concerns. With a credit or debit
card, an Internet user can order almost anything from an Internet site and have
it delivered to their home or office. Companies doing business over the
Internet need sophisticated security measures to protect credit card, bank
account, and social security numbers from unauthorized access as they pass
across the Internet (see Computer Security). Any organization that connects
its intranet to the global Internet must carefully control the access point to
ensure that outsiders cannot disrupt the organization’s internal networks or
gain unauthorized access to the organization’s computer systems and data.
Disruptions that could cause
loss of life or that could be part of a coordinated terrorist attack have also
become an increasing concern. For example, using the Internet to attack
computer systems that control electric power grids, pipelines, water systems,
or chemical refineries could cause the systems to fail, and the resulting
failures could lead to fatalities and harm to the economy. To safeguard against
such attacks, the U.S. Congress passed the Homeland Security Act in November
2002. The new law creates criminal penalties, including life imprisonment, for
disruptions of computer systems and networks that cause or attempt to cause
death. The law also allows ISPs to reveal subscriber information to government
officials without a court-approved warrant if there is a risk of death or
injury. It also enables government officials to trace e-mails and other
Internet traffic during an Internet disruption without obtaining court
approval. Civil liberties groups objected to the lack of court supervision of
many provisions in the new law.
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