Reel-to-reel audio tape recording, also called open-reel recording, is the form of magnetic tape audio recording in which the recording medium is held on a reel that is not permanently mounted in an enclosed cassette. In use, the "supply reel" ("feed reel") containing the tape is placed on a spindle or hub; the end of the tape is manually pulled out of the reel, threaded through mechanical guides and a tape head assembly, and attached by friction to the hub of the second, initially empty "takeup reel".