Introduction - Java Software Solutions: Foundations of Program Design - page 24

computer on that campus. Because the domain names are unique, many organiza-
tions can have a computer named hector without confusion. Individual depart-
ments might be assigned subdomains that are added to the basic domain name
to uniquely distinguish their set of computers within the larger organization. For
example, the cs.vt.edu subdomain is devoted to the Department of Computer
Science at Virginia Tech.
The last part of each domain name, called a top-level domain (TLD), usually
indicates the type of organization to which the computer belongs. The TLD edu
typically indicates an educational institution. The TLD com often refers to a com-
mercial business. Another common TLD is org , usually used by nonprofit orga-
nizations. During an international meeting held in Paris in 2008, a process was
started for introducing generic top-level domains (gTLD). The new rules could
result in hundreds of new gTLDs. Many computers, especially those outside of
the United States, use a country-code top-level domain (ccTLD) that denotes the
country of origin, such as uk for the United Kingdom or au for Australia.
When an Internet address is referenced, it gets translated to its corresponding
IP address, which is used from that point on. The software that does this transla-
tion is called the Domain Name System (DNS). Each organization connected to
the Internet operates a domain server that maintains a list of all computers at
that organization and their IP addresses. It works somewhat like telephone direc-
tory assistance in that you provide the name, and the domain server gives back a
number. If the local domain server does not have the IP address for the name, it
contacts another domain server that does.
The Internet has revolutionized computer processing. Initially, the primary use
of interconnected computers was to send electronic mail, but Internet capabilities
continue to improve. One of the most significant uses of the Internet is the World
Wide Web.

The World Wide Web
The Internet gives us the capability to exchange information. The World Wide
Web (also known as WWW or simply the Web) makes the exchange of infor-
mation easy for humans. Web software provides a common user
interface through which many different types of information can be
accessed with the click of a mouse.
The Web is based on the concepts of hypertext and hypermedia.
The term

KEY CONCEPT
The World Wide Web is software that
makes sharing information across a
network easy for humans.

hypertext was coined in 1965 by Ted Nelson. It describes
a way to organize information so that the flow of ideas was not constrained to a
linear progression. Paul Otlet (1868-1944), considered by some to be the father of
information science, envisioned that concept as a way to manage large amounts of
information. The underlying idea is that documents can be linked at various points