In the fictional Star Trek universe, Starfleet is the military and exploration corps of the United Federation of Planets. Starfleet Headquarters is located in San Francisco, California, Earth, Sol System, Sector 001, in the Alpha Quadrant.

Many of the Headquarter buildngs are (or will be) concentrated just East of the Golden Gate Bridge in what is now the Presidio of San Francisco, a park on the northern tip of the San Francisco Peninsula.

Starfleet consists of many branches which make up the organization, namely:

Though Starfleet ranks are comprised of many races, it is mostly populated by humans and Vulcans, two of the founders of the Federation.

Starfleet has been shown to handle diplomatic, scientific, and military missions, although their main mandate seems to be one of peaceful exploration. The flagship of Starfleet (and also of the "1st fleet", see Dominion War) is the Starship Enterprise.