Jazz standards are musical compositions which are an important part of the musical repertoire of jazz musicians, in that they are widely known, performed, and recorded by jazz musicians, and widely known by listeners. There is no definitive list of jazz standards, and the list of songs deemed to be standards changes over time. Songs included in major fake book publications (sheet music collections of popular tunes) and jazz reference works offer a rough guide to which songs are considered standards.
The most recorded jazz standard was W. C. Handy's "St. Louis Blues" for over 20 years from the 1930s onward, after which Hoagy Carmichael's "Stardust" replaced it. Today, the place is held by "Body and Soul" by Johnny Green. The most recorded standard composed by a jazz musician is Thelonious Monk's "'Round Midnight".