The Anatomy of a URL

A URL (Uniform Resource Locator) is the "address" of a particular document on the Internet. To access a particular document on a web server, the URL is typed into the address bar of a browser. A browser is a device or desktop software application that enables viewing of rendered HTML (Hyper Text Markup Language). The most widely used browsers are Microsoft's Internet Explorer, Mozilla's Firefox, Google's Chrome, and Apple's Safari.

The URL consist of a protocol, host, domain name (which includes domain and subdomain), and optionally a directory path, and file name (with or without extension).

The URL construction resembles this:
protocol://host.subdomain.topdomain/dir1/dir2/filename.ext

Example of www host:

http://www.gpc.edu/Campus_Maps/index.html
The protocol is http (Hypertext Transfer Protocol)
The host name is www
The domain name address is gpc.edu
There is no subdomain in this example.
The top-level domain is edu
The first directory is Campus_Maps
The file name is index, extension is html (common GPC extensions include htm, html, php). Most often, the index file name is not shown since it is the default file that a server retrieves when a directory with no file name is specified.

Example of a GPC virtual host (or subdomain depending on it's configuration):

https://giving.gpc.edu/townsend
The protocol is https (Secure Hypertext Transfer Protocol) used for an encrypted connection
The host name or subdomain is giving
The domain name address is gpc.edu
The top-level domain is edu
The first directory is townsend
There is no file name in this example

Example of a subdomain with www host :

Avoid this construct if possible -- it can be confusing to the user and goes against the 3-segmented (host.subdomain.topdomain) URL convention.
https://www.giving.gpc.edu/give/today/form.doc
The protocol is https (Secure Hypertext Transfer Protocol) used for an encrypted connection (on pages that obtain user input of sensitive information)
The host name is www
The subdomain is giving
The domain name is gpc.edu
The top-level domain is edu
The first directory is give, the second directory is today
The file name is form.doc