"Take the 'A' Train" is a jazz standard by Billy Strayhorn that was the signature tune of the Duke Ellington orchestra.
Billy Strayhorn
Jazz standards are musical compositions that 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 and jazz reference works offer a rough guide to which songs are considered standards.
The Original Dixieland Jazz Band, from the original 1918 promotional postcard while the band was playing at Reisenweber's Cafe in New York City. Shown are (left to right) Tony Sbarbaro (aka Tony Spargo) on drums; Edwin "Daddy" Edwards on trombone; D. James "Nick" LaRocca on cornet; Larry Shields on clarinet, and Henry Ragas on piano.