The Dorian mode is the scale obtained by playing the white keys of the piano from D up to the next D: D–E–F–G–A–B–C–D. Moved to C it becomes C–D–E♭–F–G–A–B♭. It sounds minor because of its flat third, but compared with the natural minor scale its sixth note is a semitone higher (A instead of A♭ in C), and that one change gives it a softer, less tragic colour.
Dorian is the scale most closely associated with modal jazz. Miles Davis’s “So What”, recorded in March 1959 for Kind of Blue, spends sixteen bars on D Dorian, moves up a semitone to E♭ Dorian for eight bars and then returns, giving soloists long stretches on a single mode instead of fast-moving chords. Since the mode fits a minor seventh chord perfectly, Dorian melodies over a looping Dm7 or Dm9 are a staple of jazz lo-fi.