Slash notation is a form of purposefully vague musical notation which indicates or requires that an accompaniment player or players improvise their own rhythm pattern or comp according to the chord symbol given above the staff. On the staff a slash is placed on each beat (so that there are four slashes per measure in 4/4 time).[1]

Slash notation and rhythmic notation may both be used in the same piece, for example, with the more specific rhythmic notation used in a section where the horn section is playing a specific melody or rhythmic figure that the pianist must support, and with slash notation written for the pianist for use underneath improvised soli.