Stepping
Once a typically developing infant has learned to balance and reach to the side, they will usually start to take a step sideways when reaching for toys that are placed just beyond arms reach.
These first steps provide the infant with the experience of shifting the COM over one LE, and then lifting the contralateral foot up off the supporting surface and moving it sideways before shifting the COM laterally and transferring the weight onto this LE.
Video clip: Roan stepping in supported standing
Cruising
Cruising differs from stepping in that the infant takes a series of steps with a defined stance and swing phase for each lower extremity. There is a smooth transition from stance to swing phase for each LE.
During the stand phase to COM is translated laterally and the stance hip moves from abduction into adduction as the trunk moves laterally over the supporting limb.
Video: Will 13m cruising
Max cruising
Video clip: Max cruising