CHAPTER 7: The Internet, Intranets, and Extranets
.The Internet is like many other technologies—it provides a wide range of services,
some of which are effective and practical for use today, others that are still
evolving, and still others that will fade away from lack of use.
The Internet started with ARPANET, a project sponsored by the U.S. Department of Defense
(DoD). Today, the Internet is the world’s largest computer network. Actually, it is a collection of
interconnected networks, all freely exchanging information. The Internet transmits data from
one computer (called a host) to another. The set of conventions used to pass packets from one host
to another is known as the Internet Protocol (IP). Many other protocols are used with IP.
The best known is the Transmission Control Protocol (TCP). TCP is so widely used that many
people refer to the Internet protocol as TCP/IP, the combination of TCP and IP used by most
Internet applications. Each computer on the Internet has an assigned address to identify it from
other hosts, called its Uniform Resource Locator (URL).
People can connect to the Internet in several ways: via a LAN whose server is an Internet host,
or via a dial-up connection, high-speed service, or wireless service. An Internet service provider is
any company that provides access to the Internet. To use this type of connection, you must have
an account with the service provider and software that allows a direct link via TCP/IP.
. Originally developed as a document-management system, the World Wide Web is
a hyperlink-based system that is easy to use for personal and business applications.
The Web is a collection of tens of millions of servers that work together as one in an Internet
service providing information via hyperlink technology to billions of users worldwide. Thanks to
the high-speed Internet circuits connecting them and hyperlink technology, users can jump
between Web pages and servers effortlessly—creating the illusion of using one big computer.
Because of its ability to handle multimedia objects and hypertext links between distributed
objects, the Web is emerging as the most popular means of information access on the Internet
today. As a hyperlink-based system that uses the client/server model, the Web organizes Internet
resources throughout the world into a series of linked files, called pages, accessed and viewed
using Web client software, called a Web browser. Internet Explorer, Firefox, and Safari are three
popular Web browsers.
A collection of pages on one particular topic, accessed under one Web domain, is called a Web
site. Hypertext Markup Language (HTML) is the standard page description language for Web
pages. The HTML tags let the browser know how to format the text: as a heading, as a list, or as
body text, for example. HTML also indicates where images, sound, and other elements should be
inserted. Some newer Web standards are gaining in popularity, including Extensible Markup
