Cybertron is the home world of the Autobots and Decepticons in the assorted stories in the fictional Transformers universes. The capital of Cybertron is the Iacon Hub City and serves as the base of operations for the Autobots. Other cities are Kaon (the Decepticon capital), Perihex, Antihex, Uraya, Polyhex, Vos, Tarn, Nova Cronum and crystal city (destroyed).
Cybertron, as presented in the original The Transformers animated series, was considerably smaller than the planet Earth. Entirely metallic on the surface, some of the lowest levels of Cybertron consist of rock and dirt, suggesting a natural beginning to the planet. Its gravity is light enough that humans are able to traverse the surface without any trouble, and it possesses a breathable atmosphere.
The position in continuity of the 1990s Transformers series, Beast Wars and Beast Machines is a difficult one to precisely define. They most certainly exist in the same universe as a Generation 1, similar to the original animated series or Marvel Comics series, but although they most frequently show their lineage through references to the cartoon, references to the Marvel series are also featured - the result of the way that past G1 stories were treated as "mythological," in the way that famous legends can have numerous tellings.