Changing the pitch of a piece of music. The intervals between the individual tones (intervals) remain unchanged. However, transposition often requires a change of key, which is why the key signature and accidentals have to be changed.

The goal of transposition is usually to make the piece better playable or singable for a specific context. E.g., on the ukulele in standard reentrant tuning, the lowest note is a C; pieces in which lower notes occur need therefore to be transposed (set higher) so that they can be played on the ukulele. In addition, some keys (such as E major) are relatively difficult to play on the ukulele because of complicated finger positions. To facilitate playing, a simpler key can be chosen.

A simple technical solution for the transposition on a string instrument is the use of a capo.