Human memory is a critical part of cognition and identity. It is usually divided into short-term memory, which is of limited capacity and is retained for no more than seconds or minutes, and long-term memory, which is unlimited and lasts for years, possibly indefinitely. Between the two is mezzanine memory, the memories you have of what you did in the last few hours, which hasn't had time to pass yet into long-term memory, but this is far less well studied or understood.
Used in glossary entries: long-term memory, mezzanine memory, short-term memory