Microsoft Office Tutorials and References
In Depth Information
Figure 6 identifies the parts of a URL.
Structure of a URL
Web pages transmitted over the Internet use a communication protocol for transferring
information. A protocol is a standardized procedure that computers use to exchange data.
The most common protocol used on the Internet is the Hypertext Transfer Protocol
(HTTP) . A Web page whose URL begins with “http://” indicates that the Web browser
should use HTTP when retrieving the page.
The server address portion of a URL may consist of numbers or letters. Every computer
on the Internet has an IP (Internet Protocol) address . An IP address is a unique number
that consists of four sets of numbers from 0 to 255, separated by periods (such as
126.96.36.199), and identifies the specific server or computer connected to the Internet.
Because IP addresses can be difficult for people to remember, domain names were cre-
ated as another means of identifying computers and servers connected to the Internet. A
domain name is a name that identifies one or more IP addresses, such as course.com.
Domain names are used in the server address portion of a URL to identify a particular
Web site. The URL shown in Figure 6 has a domain name of centralpenn.edu. In the
server address for this URL, www indicates that the server is a Web server; centralpenn is
the identifying name chosen by the organization to which the Web site belongs, in this
case Central Pennsylvania College; and .edu indicates that the server is operated by an
educational entity. Other common types of Web servers in the United States are .com
(commercial business), .org (not-for-profit organization), and .gov (government). A more
complete list is given in Figure 7.
Types of Web servers
Web Server Types
Businesses and other commercial enterprises
U.S. government agencies, bureaus, or departments
U.S. military units or agencies
Network service providers or resources
Other organizations, usually charitable or not-for-profit
In addition, all Web pages stored on Web servers have unique pathnames, just like files
stored on a disk. The pathname in a URL includes the folder name(s) where the Web page
is stored and its filename and file extension. The file extension for most Web pages is
either .htm or .html. In the sample URL shown in Figure 6, the pathname that follows the
server address www.centralpenn.edu sp ecifies a file named index.html , which is stored in
a folder named library .
Not all URLs include a filename. If a URL does not include a filename, most Web
browsers will load the file named index.htm. The index.htm filename is the default name
for a Web site’s home page.