This jazz standard is the first tune on Miles Davis’ classic record, “Kind of Blue.” It’s the top jazz album of all time as measured by sales.
Bill Evans starts this tune out with a nice intro on this tune, but in practice most groups don’t play it exactly like the record. That would be an interesting thing to do, since most groups don’t seem to go to that effort. The bass player plays the melody of this tune. So What has the same changes as John Coltrane’s tune “Impressions,” the latter having a faster tempo and melody. It makes sense that Coltrane would steal the changes for his own tune, having cut his teeth in Miles’ band and performing So what regularly.
This is perhaps the first recorded example of modal jazz. It has very few chord changes. It’s an AABA form, using Dorian minor harmony. The B section is a half-step up from the A section. Most pianists and guitarists, including Bill Evans, like to use diatonic fourth chords when comping. For example, DGCFA up to EADGB up to FBEAC is a nice progression on the D-7 using diatonic fourth stacks with a third on top. Play around with it, and LISTEN! Even non-guitarists and non-pianists should experiment with this idea on the piano to help understand this idiomatic harmonic movement even when the chord doesn’t change.