Footsteps provide a way to animate a biped. In viewports, footsteps represent support periods in space for the biped's feet. Moving or rotating footsteps in space is done in the viewports. The footstep position and orientation in the viewport controls where the biped will step. See Footstep Animation.
In Track View — Dope Sheet, each footstep appears as a block that represents a support period in time for each of the biped's feet. Moving footsteps in time is done in Track View — Dope Sheet.
There are three ways to create footsteps for the biped. The first way is to place footsteps individually, one at a time. The second way is to invoke Biped's multiple footstep creation tools to create a walk, run, or jump animation. The third way is to extract footsteps from raw motion-capture data.
A big advantage of the footstep method is the natural adaptation of the biped that occurs when the footsteps are edited in time and space. Also, you can reposition all of the footsteps to move the entire animation.