Reel-to-reel, open reel tape recording is the form of magnetic tape audio recording in which the recording medium is held on a reel

Reel

A reel is an object around which lengths of another material are wound for storage. Generally a reel has a cylindrical core and walls on the sides to retain the material wound around the core...

, rather than being securely contained within a cassette.

In use, the supply reel or feed reel containing the tape is mounted on a spindle; the end of the tape is manually pulled out of the reel, threaded through mechanical guides and a tape head

Tape head

A tape head is a type of transducer used in tape recorders to convert electrical signals to magnetic fluctuations and vice versa.-Principles of operation:...

 assembly, and attached by friction to the hub of a second, initially empty takeup reel.