What is an Address?
Two commonly asked questions these days are "What's your e-mail address?" and "What's the URL?" Generally, the first question is asking where to send information, while the second is asking where to get information. The answer to the first question is usually something like email@example.com. The answer to the second question is usually something like "http://www.newspaper.com".
What do these answers mean?
As stated previously an e-mail address is something like "firstname.lastname@example.org", pronounced "MYNAME at COMPANY dot COM". An email address consists of two parts that are divided by an "@" sign.
The portion to the left is like the name line on a letter, it identifies a particular person and usually is composed of the person's name. Typical names look like this:
The name is assigned by the system or network administrator who is managing the email system and follows rules that have been established by the company providing the e-mail service. Sometimes the name portion of the e-mail address is referred to as a mailbox.
The portion to the right of the "@" sign is the name of the computer system that is providing the e-mail service. This name is usually the name of the company that owns the computer system followed by a "dot" and an abbreviation that represents the "domain" or group of names which the organization falls under. Examples of these "top level" domains are "edu", "com", and country codes such as "fr" for France and "jp" for Japan. When an e-mail is sent the portion of the address to the right of the "@" sign is used to find the destination computer of the email.
A Uniform Resource Locator (URL) is commonly used to identify a computer that provides world wide web service. It usually looks something like "http://www.newspaper.com". This address also consists of two parts. In this case the two parts are separated by the "//". The portion to the left means find the world wide web service that is located at the computer identified to the right of the "//". The portion to the right is the name of the computer that is providing the world wide web service. Its name is composed of parts that are similar to those described for the name of an email computer. Sometimes the portion on the right contains additional information that identifies a particular document at the web site.
For example, http://www.newspaper.com/sports/article1.html would identify a specific article in the sports section of the newspaper.
Source: R. Plzak