The depth drop is a partial plyometric exercise and the base of the depth jump used to develop the ability to absorb force.
Stand at the front edge of a box or bench. Step off to drop and land on both feet together, absorbing the force with a bend of the knees and hips but arresting the downward motion quickly.
The depth drop develops the ability of the legs to absorb force safely and productively while maintaining the desired position and balance. This is useful for the jerk dip and drive, and receiving cleans in particular. It’s also the base of the depth jump exercise.
Depth drops are far more taxing on the body than they may appear, so be conservative with volume and frequency. A few sets of 3-5 reps is plenty.