.gov is the generic top-level domain used by the United States federal government. It was one of the original top-level domains, established in January 1985.
The U.S. is the only country that has a government-specific top-level domain in addition to its ccTLD. Other countries typically use a second-level domain for this purpose, e.g., .gov.uk for the United Kingdom, .gc.ca for Canada, .go.jp for Japan, .govt.nz for New Zealand and .gov.it for Italy. Since the United States controls the .gov Top Level Domain, it would be impossible for another country to create a domain ending in .gov, for example .jp.gov.
Many U.S. federal agencies still use .fed.us rather than .gov. The Department of Defense and its subsidiary organizations use .mil.
All governments in the U.S. are allowed to use .gov, such as atlantaga.gov for the city of Atlanta, and georgia.gov for the U.S. state of Georgia.
The usage of .gov as a gTLD controlled only by the US is controversial, as some people believe this to be an example of arrogance by the US - such views hold that usage of .fed.us or a new second level domain of .gov.us would be more suitable.
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