Information Technology Reference
In-Depth Information
The Internet began in the late 1960s and 1970s as a small net
work, initially funded by the Advanced Research Projects Agency
(ARPA) of the United States Department of Defense (DoD), called
ARPAnet. The network expanded with funding from both the DoD
and the National Science Foundation (NSF), but remained as a re
search enterprise through the 1980s. In 1991, the NSF phased out
various commercial restrictions and began a program to turn the
Internet over to the private sector. National access points (NAPs)
now run national operations within the United States, and Internet
service providers (ISPs) work regionally and on the local level. The
network is designed so that new networks can join without affect
ing current networks. This has allowed for explosive growth; in the
United States alone, some 1300 companies now provide national
service, and some regions have as many as 1500 companies that
provide local service. In order to function, all of these groups must
conform to standards that are set by international organizations.
Outside the United States, governments organize Internet access in a
similarly cooperative manner.
All locations on the Internet are described at three levels: a do
main name, an Internet Protocol number (IP number), and an
Ethernet address. The domain name provides an easily remembered
identification (for example, cs.utexas.edu for the computer sciences
department at the University of Texas at Austin), the IP number
provides a technical identification (128.83.139.9 for cs.utexas.edu),
and the Ethernet address identifies a specific electrical board
plugged into the local computer. Desktop computers often are as
signed IP addresses manually, but laptop computers may operate
through DHCP (Dynamic Host Configuration Protocol), through
which they request a new IP address whenever they are plugged into
the network.
When your computer is connected to the Internet, you may use
a Web browser to identify materials and have those materials dis
played. Web pages are identified through a specific address; the suf
fix of that address often identifies the type of document being re
trieved. Web pages often contain formatting information written in
the Hypertext Markup Language (HTML), and Web browsers use
these formatting instructions to display data on your screen.
