A Domain Name is a textual version of an IP Address, the number that points to a particular website. For example, the number 22.214.171.124 is the IP Address for yahoo.com. Each domain name on the Internet corresponds to such numbers.
Without domain names, each and every website would have to be recalled by a number like this, similar to the telephone system, but much more difficult to remember. For this reason, domain names were introduced, and have made navigation on the net much simpler.