| An alias for an IP address on the Internet. Generally, every individual computer machine connected to the Internet is assigned an IP number in the format 123.456.789.012. Since these numbers are difficult to remember than normal English language words, an alias is given to IP numbers that makes it easier to remember. For Example, everything2.com is hosted on a machine represented by 206.170.14.131.
Generally, a domain name constists of three parts. For Example, take www.everything2.com.
The first part (from the right), com, tells us that the entity is represented by a Company. There are many other variations - net for Networks, org for Organisations, and country-specific like - us for USA, in for India, uk for United Kingdom, and so on.
The second part, everything2, is a unique name that identifies the entity within that .com, .net, .org, or whatever. This means - everything2.com and everything2.net can be different entities.
The third part, www, refers to the sub-domain of the entity. There can be many sub-domains - like fun.everything2.com, usa.everything2.com, etc.
To get a domain name, an individual or company has register it via a Domain Name Registrar for specific amount of money as per the registrar's policy. There are hundreds of such organisations in the world and for each domain. One such, and the first, organisation is Network Solutions at http://www.networksolutions.com . | 
