Prosimians are a group of proto-primates. It includes all living and extinct strepsirrhines (lemurs, lorises, and adapiforms), as well as the haplorhine tarsiers and their extinct relatives, the omomyiforms.
They have characteristics that are more "primitive" (ancestral or plesiomorphic) than those of simians (monkeys, apes, and humans).
Prosimians are a paraphyletic group and not a clade (a group of an ancestor and all its descendants). Tarsiers share a more recent common ancestor with all simians than with the strepsirrhines. Consequently, the term "prosimian" is no longer an official term in taxonomy. It is still used to compare their behaviour with that of other primates.
Prosimians are the only primates native to Madagascar, but are also found throughout Africa and in Asia.