A domain name is the registered name of an individual or organizations appearance on the internet. Domain names have at least two parts and each part is seperated by a dot (e.g. www.telecomabc.com). The part at the right is called the top level domain. This can be either country specific (e.g. .nl or .uk) or generic (e.g. .com or .org). The part at the left of the top level domain has to be unique for that top level domain.
Domain names are used because they are easier to remember than an Internet address. The translation of a domain name to an internet address is done by a domain name server (DNS).