Notation is a set of visual instructions designed to represent musical sound. Notation can take many forms but the method most familiar to western art music has been in a process of continuous development since plainchant was written down in the 9th century. As a language, all notation is necessarily inaccurate since there is no direct visual analog for sound. Asa result, performers have to interpret the notation in order to produce the notation in order to produce the most accurate possible recreation of the composer's intentions.