Starbase 218 is a Federation starbase administered by Starfleet.
In 2369, the USS Enterprise-D took up new crewmembers here, including nurse Beck and Lieutenant Commander Nella Daren. (TNG: "Lessons")
The Enterprise-D was en route to Starbase 218 when the ship encountered a Kataan probe in "The Inner Light". The reference to the starbase was cut from the episode and is only mentioned in the script.