This was the opening track on Kind Of Blue, which is arguably the biggest-selling Jazz album of all time. It was recorded by Miles Davis in 2 days giving only brief instructions to a new band - yet all tracks were recorded in one take. It is also counted by many as the greatest Jazz album of all time and ranks at or near the top of many "best album" lists. Rolling Stone magazine, for instance, placed it 12th on their list of the 500 greatest albums of all time.

In 2007 this was voted the best-ever Jazz record in a poll of listeners of the UK radio station Jazz FM.

George Cole, who wrote The Last Miles: The Music of Miles Davis, 1980-1991, explains why Davis is so important: "Miles Davis is to jazz is what Mozart is to classical music or The Beatles are to popular music. He is by far the most influential jazz musician of all time and it's unlikely that anyone will ever supplant this position. He started out as a teenager playing bebop (a frenetic style of jazz) with the saxophonist giant Charlie Parker, and ended almost 50 years later, combining jazz with hip-hop. He recorded the best known album in jazz (Kind of Blue) while still in his early 30s and it contains the best known jazz track: 'So What.'" (For more on Miles Davis,read our interview with George Cole.)

This was one of three tracks on Kind Of Blue that was originally recorded in the wrong key later to be tidied up on re-releases (the other two were "Freddie Freeloader" and "Blue in Green").