The past is the portion of the timeline that has already occurred; it is the opposite of the future. It is also contrasted with the present.
The past is the object of such sciences as history, archaeology, archaeoastronomy, historical linguistics, geology (historical geology), paleontology, paleobotany, paleoethnobotany, palaeogeography, paleoclimatology, cosmology.
Related topics: memory, retro, antiquarian, fossil