The great alto saxophonist Cannonball Adderly was a part of Miles Davis' band when Davis wrote many songs based on modes. The above lick (transcribed for guitar) features Adderly playing ideas based on the G dorian mode, over a Gminor chord.
Okay, now we've learned some of the performance basics of the dorian mode, it's time to tackle a tricky subject - where the mode comes from, and when to go about using it.

