Domain names are used to identify one or more IP addresses. The Domain name represents a dozen IP addresses. Rather than typing a complicated set of numbers (the IP address) into your browser, you can just type in a domain name. Domain names are used in URLs to identify particular Web pages.
Every domain name has a suffix that indicates which top-level domain (TLD) it belongs to. There are only a limited number of such domains. For example:
org - Organizations (nonprofit)
gov - Government agencies
edu - Educational institutions
mil - Military
com - commercial business
net - Network organizations