Heel-toe is essentially what it sounds like - rather than a regular foot pedal press, the drummer should move his foot rapidly in a way that the heel presses and releases the pedal in time for the toe to come down and hit the pedal again almost immediately. It takes a considerable amount of practice to learn and master, however it is a technique that is extremely useful for advanced drummers - especially in some drum fills in metal music which involve alternations between a drum and the foot