Electronic mail (E-mail) may be the most popular use of the Internet today. It allows people to send written messages, files, and pictures to other people, anywhere in the world. All you need is an E-mail account and access to the Internet in order to receive messages. E-mail messages are transferred over the Internet to the recipient's E-mail address, as specified by the originator of the message.

Web-based E-mail is the technology that provides the access of an E-mail account by a web browser. Using it is as easy as browsing to the web site, logging on and sending or receiving E-mail messages. Using the web browser as an E-mail client makes the E-mail account accessible from any computer connected to the Internet.

An E-mail address is a single line in the following format: user@host.domain
The part before the '@' sign is called the User Name. When you sign up, you can choose your own user name, as long as no one else has previously chosen it. This is due to the fact that user names are unique. After the '@' sign is the name of the system under which the user's E-mail account resides, in this case: host.domain.
There are several types of domains. Companies or commercial organizations use "com", while educational institutions use "edu" or "ac". Government addresses use "gov" and military addresses use "mil". Gateways and other administrative hosts for a network use "net", and private organizations use "org".

Countries also have their own domains. Some examples of Country domains are:

au      Australia 
br       Brazil
ca      Canada
de      Germany
uk      United Kingdom