The Smithsonian Institution Archives facilitates the transfer of permanent and temporary records from Smithsonian Institution museums and other units to either the Archives or the Records Center. Permanent records are retained by the Archives in perpetuity, while temporary records are maintained at the Records Center for a scheduled period of time before being destroyed. Transferring units must follow a series of steps before the transfer or destruction of records can occur. These procedures apply to most transfers of records, but different instructions may be warranted for unusual circumstances such as oversize or undersize materials, as well as for photographic, audiovisual, or electronic records. In such circumstances contact the Archives. For definitions of commonly used archival terms consult the glossary.