He is described as a grisly monster with a hundred dragons' heads, who was conquered and cast into Tartarus by Zeus.
It is to be distinguished from Tartarus, the place of punishment for the wicked.
These original gods were Tartarus, Gaia (earth), Eros (perhaps - also given as son of Ares and Aphrodite), Nyx (night) and Erebus.
In Hesiod (Theogony, 264) they are the three sons of Uranus and Gaea - Brontes, Steropes and Arges, - storm-gods belonging to the family of the Titans, who furnished Zeus with thunder and lightning out of gratitude for his having released them from Tartarus.
In later writers Tartarus is the place of punishment of the wicked after death, and is used for the underworld generally.