In the Star Trek universe, Starfleet is a fleet of starships dedicated to keeping the peace around the universe and providing the United Federation of Planets (UFP) with a tool for both research and defense missions, diplomatic representation and particularly exploration of the universe in search for sentient life. It is closely related and under the jurisdiction of the United Earth Space Probe Agency, an Earth based organization which is also responsible for the exploration of space.
Each USS Enterprise is operated by members of Starfleet, making the majority of Star Trek's characters, especially the protagonists, members of Starfleet. The central headquarters of Starfleet are based on Earth in Fort Baker, California, north-east of the Golden Gate Bridge. However, episode of the television show show many starbases across the universe operated by Starfleet, serving as either orbital docking stations or planet facilities.
Branches of Starfleet
There are many different components of Starfleet, serving individual roles. The major ones include:
Starfleet Command is responsible for overseeing the various other sections of Starfleet. It also commands a selection of starbases across the universe, including administrative and support outposts which are partly responsible in subspace communications. The movie Star Trek: The Motion Picture places Starfleet Command in the Starfleet Headquarters in California, very close to the headquarters of the Council of the United Federation of Planets. It is under the jurisdiction of the United Earth Space Probe Agenc (UESPA).
Starfleet Academy is an Earth-based training facility for people who wish to become Federation and Starfleet officers. Training takes place across four years and mostly takes place on site. The Academy's motto is "Ex Astris, scientia", which means "From the stars, knowledge". The training facility can be used by any citizens of the Federation, but non-Federation citizens require a letter of recommendation from a Starfleet command level officer before they can take the required entry examination.