How the Internet Works
The Internet was created for the U.S. Department of Defense as a tool for communications. Today, the Internet is a network of interconnected networks. It is a huge, cooperative community with no central ownership. The Internet connects thousands of networks and more than 100 million users around the world. The Internet carries messages, documents, programs, and data files that contain every imaginable kind of information for businesses, educational institutions, government agencies, and individuals.
All computers on the Internet use TCP/IP protocols. Any computer on the Internet can connect to any other computer. Individual computers connect to local and regional networks, which are connected together through the Internet backbone.
A computer can connect directly to the Internet, or as a remote terminal on another computer, or through a gateway from a network that does not use TCP/IP.
Every computer on the Internet has a unique four-part numeric IP address, and most also have an address that uses the domain name system (DNS). DNS addresses have two parts: a host name (a name for a computer connected to the Internet) followed by a domain that generally identifies the type of institution that uses the address. This type of domain is often called top-level domain. For example,
many companies have a DNS address whose first part is the company name followed by ".com" — ibm.com (International Business Machines Corp.). Some large institutions and corporations divide their domain addresses into smaller subdomains.
For example, a business with many branches might have a subdomain for each office — such as boston.widgets.com and newyork.widgets.com. In 1996 a new set of top-level domain names was created because it was difficult for organizations to find suitable domain names for their Internet sites, for example .firm (businesses or firms), .shop (business that offer items for purchase over the Internet),.arts (organizations promoting artistic or entertainment activities over the Internet. Geographic domains usually identify the country in which the system is located, such as .ca for Canada or .fr for France.
The Internet has a lot of uses:
— Inexpensive electronic mail systems enable you to exchange messages with any other user anywhere.
— TELNET allows a user to operate a second computer from his or her machine.
— File Transfer Protocol (FTP) is the Internet tool for copying data and program
files from one computer to another.
— News and mailing lists are public conferences distributed through the Internet and other electronic networks.
— Chats are public conferences, conducted in real time, where people discuss topics of interest.
The World Wide Web
One part of the Internet is the World Wide Web. It was created in 1989 at the European Particle Physics Laboratory in Geneva, Switzerland as a method for incorporating footnotes, figures, and cross-references into online hypertext documents.
A hypertext document, or a Web page, is a specially encoded file that uses the hypertext markup language (HTML). This language allows a document's author to embed hypertext links, or hyperlinks, in the document. A collection of related Web pages is called a Web site. Web sites are housed on Web servers, Internet host computers that often store thousands of individual pages. Copying a page onto a server is called posting the page. Downloading a page from the Web server to your computer for viewing is commonly called "hitting" the Web site.