A slur is a symbol in Western musical notation indicating that the notes it embraces are to be played without separation (that is, with legato articulation). A slur is denoted with a curved line generally placed over the notes if the stems point downward, and under them if the stems point upwards:
- For bowed string instruments, the notes should be played in one bow stroke.
- For guitars, the notes should be played without plucking the individual strings (hammer-ons and pull-offs).
- For wind instruments, the notes should be played without rearticulating each note (tonguing), except in trombone.
- For vocal music, slurs are usually used to mark notes which are sung to a single syllable (melisma).
A slur can be extended over many notes, sometimes encompassing several bars. In extreme cases, composers are known to write slurs which are near-impossible to achieve; in that case the composer wishes to emphasise that the notes should be performed with as much legato as possible.