What is a domain name?
A domain name is like a big neon sign board that points to a particular location in this case a server and asks the server to return the information that the site visitor is looking for. It is quite simply the name of your site for example www.yahoo.com is a domain name so would be www.mysite.com
Domain names are unique, so there will only be one domain name of its kind on the internet. There are many parts to the domain name. The first part www is a sub domain of the domain itself. It is not necessary to include it and may website owners prefer to go ahead without it.
Similarly you can choose the ending of your domain name. It doesn’t always have to be com you can use other letters that signify your country or the type of business you intend to run. You can use .US, .Com, .Biz and so on . These are called TLD's and are usually 4/5 letter endings but there are a multitude of them to choose from.