What does an archivist do? How is that different from a historian or collector?

Archivists are responsible for collecting, arranging, preserving and providing access to permanent historical records of enduring value, not writing or interpreting history. Historians gather, organize, analyze, interpret and describe information about the past by drawing on a wide variety of historical resources. Collectors often purchase and sell items through rare book dealers or auctions. Archivists do not typically purchase materials, but instead receive them as donations.