It was the sole planet orbiting its isolated star and had almost no metals. The nearest planet was Anacreon, 8 parsecs (26 light years) away. Being on the fringe of the galaxy, there are almost no stars in the sky. It lay on the edge of the Galaxy that was opposite the planet Siwenna. It was the planet farthest from the Galactic Centre; its name reflects that fact: Latin terminus means 'end of the line'.
It had a very high water/land ratio. The only large island was the one on which Terminus City lay. A total of 10,000 inhabited islands existed on the planet. The climate was mild.
Prior to human occupation, there was some life on Terminus. However, once humans arrived (along with their supporting species), these native life forms were crowded out and became extinct.
The capital of Terminus Planet is Terminus City. Terminus City is home to a number of places, including:
- City Hall—the primary administrative building of the Foundation, including the Council Chambers and Mayor's Office
- City Hall Park
- Cyclopedia Square
- The Hardin Building—a public apartment complex
- Mallow Hall—a concert venue
- The Salvor Hardin Museum of Origins—more commonly called the Hardin Museum, a museum of Foundation history, known to house the copies of the original Encyclopedia Galactica
- The Seldon Vault—where messages recorded by Hari Seldon before his death were played to relay important information to the citizens of the Foundation, around the times of the Seldon Crises.
- Terminus Spaceport
- Ultimate Spaceport
Three other cities are known: Agyropol, Newton City, Stanmark (Arkady Darrell's hometown).
With the Galactic Empire in fatal decline, Hari Seldon, inventor of the science of Psychohistory, predicted a 30,000 year interregnum of barbaric dark ages until the rise of a New Empire. So Seldon created a plan to shorten this interregnum from 30,000 years to 1,000 years.
Seldon asked Las Zenow, chief librarian of the Imperial Library of Trantor to undertake a search to find a suitable planet, according to Seldon's criteria. Zenow, following a lengthy search, found Terminus, which had been uninhabited through the five centuries after its discovery.
Seldon manipulated the totalitarian Commission of Public Safety that ruled the Galactic Empire to exile his project to Terminus. The founding population consisted of 100,000 especially healthy scientists, whose ostensible purpose it was to publish an Encyclopedia Galactica. In actuality, their job would be to preserve science and technology, and reconquer the Galaxy to form the Second Empire.