In music notation, a ligature is a symbol that marks a set of musical notes which are to be played in such a way as to form a single musical phrase. As such, it is also known as a phrase mark, and takes the form of a curved line extended over the notes.

A ligature is also a device which holds a reed on to the mouthpiece of some woodwind instruments such as the saxophone and clarinet.

A ligature can be made out of either metal, such as brass, or it can be made of leather.