Chapter 2 - Browsing the Web

The World Wide Web consists of a vast collection of documents that feature text, pictures, sound, animation, and video.  These documents are called web pages.  A collection of web pages makes up a web site.  The primary web page of a web site is called a home page.  Usually web sites include multiple web pages.

A web browser must send a request for a copy of the web page to the web server before it can be displayed.  To do this, a web browser uses the domain name and URL to find the IP address.  This address is where the web page is stored.  An IP address or Internet Protocol address is a number that uniquely identifies each computer or device connected to the Internet.  It is similar to how a postal service relies on a mailing address to make sure that mail is delivered to the correct recipient.

IP addresses are difficult for people to remember therefore web servers typically are referenced by a domain name.  A domain name is a text alias for one or more IP addresses.  Domain names are grouped by top-level domain (TLD).  TLD is an abbreviation that identifies the type of organization associated with the domain.  For example, .edu is the TLD abbreviation for Educational Institutes and .gov is the TLD abbreviation for Government entities.  Each web page also has its own unique address called a Uniform Resource Locator (URL).  The URL is made up of 4 parts.  First the protocol, then the domain name, next the path, and lastly the file name.