During production of early episodes of the original series, several details of the makeup of the Star Trek universe had yet to be worked out, including the operating authority for the USS Enterprise.

The terms Star Service ("The Conscience of the King"), Spacefleet Command ("The Squire of Gothos"), United Earth Space Probe Agency ("Charlie X" and "Tomorrow Is Yesterday"), and Space Central ("Miri") were all used to refer to the Enterprise's operating authority, before the term "Starfleet" became widespread from the episode "Court Martial" onwards.

Other background props included additional UESPA references, such as Captain Jean-Luc Picard's family album in Star Trek Generations.

During the production of Star Trek: Enterprise, some larger Starfleet insignia designs included the name "United Earth Space Probe Agency".

Multiple Star Trek: Enterprise episodes refer to Starfleet having started operation some time between 2112 and 2136, when it funded research begun by Zefram Cochrane and Henry Archer, which led to the first successful flight of Warp-3 vessels in the 2140s.

[1] This research is said to have evolved into the NX Program, which led to Starfleet launching its first Warp 5–capable starship, Enterprise (NX-01), in 2151, followed by Columbia (NX-02), in 2155, as well as other vessels.

This is said not to be a human construct, but stems from policies originally implemented by the Vulcans, who regarded an alien civilization's attainment of warp speed as the reason for making first contact with them.

Starfleet Headquarters is shown to be located on Earth, northeast of the Golden Gate Bridge in the present-day Fort Baker area.

Overlooking the Command from the other side of the Golden Gate is the permanent site of the Council of the United Federation of Planets in what is now the Presidio of San Francisco.

In the 2013 sequel, Montgomery "Scotty" Scott discovers a covert Starfleet facility, near Jupiter, that has built a much larger Federation warship, USS Vengeance.

The Starfleet Engineering Corps (also called the Starfleet Corps of Engineers) is mentioned in several episodes in conjunction with projects such as hollowing out the underground laboratory complex inside the Regula I asteroid in Star Trek II: The Wrath of Khan, the design of the Yellowstone-class Runabout in the alternate timeline in the Star Trek: Voyager episode "Non Sequitur", and devising a defense against the Breen energy-dampening weapon in the Star Trek: Deep Space Nine episode "When It Rains..." As a result of these successes, Starfleet engineers gained a reputation as the undisputed masters of technological adaptation and modification.

In the non-canon Star Trek: New Frontier novels the series main character Mackenzie Calhoun was once a Starfleet Intelligence operative.

Although Humans are the most-often-seen crew members onscreen, Starfleet is shown to be composed of individuals from over 150 species, with Vulcans perhaps being the most common aliens seen.

For example, Star Trek: TNG's Ensign Ro Laren, a Bajoran aboard the USS Enterprise-D; her fellow Bajoran Kira Nerys, who was field-commissioned as a Starfleet commander so that she could aid the Cardassian resistance during the Dominion War; and Ferengi Nog, who enters Starfleet Academy in season four of Star Trek: Deep Space Nine; all were from non-member planets.