top-level domains

On the Internet, the highest category of host name, which either signifies the type of institution or the country of its origin.

In the United States, the most common top-level domains include:

com A commercial organization. Most companies end up in this category.
edu An educational establishment such as a university.
gov A branch of the U.S. government.
int An international organization such as NATO or the United Nations.
mil A branch of the U.S. military.
net A network organization.
org A nonprofit organization.

Most countries also have unique domains named after their international abbreviations; for example, ca represents Canada, uk represents Great Britain, and jp represents Japan.