Kubrick wanted his film to explore «the reasons for believing in the existence of intelligent extraterrestrial life» and what it would mean if we discovered it
Kubrick encouraged people to explore their own interpretations of the film, and refused to offer an explanation of
Clarke's novel explicitly identifies the monolith as a tool created by extraterrestrials that have been through many stages of evolution, moving from organic forms, through biomechanics, and finally to a state of pure energy.