what is difference between normal domain and 3rd level domai

[cookies186]

Hello friends
can any body tell me.
what is difference between normal domain and 3rd level domain?

[ewebmaster]

Domain names are names that uniquely identifies a site (e.g., a web site or ftp site) on the Internet or other TCP/IP (transmission control protocol/Internet protocol) networks and serve as user-friendly substitutes for difficult-to-remember, numeric IP addresses.

A third-level domain is the next highest level in the domain name hierarchy.The third level domain is typically used to refer to a specific server within an organization. In larger organizations each division or department might have its own third level domain