CrossFit is

a strength and conditioning system built on constantly varied, if not randomized, functional movements executed at high intensity. Let’s give life to this description and see how this program, honed from years of clinical experience, goes about forging elite fitness. Man’s world, nature, is full of movement. Our standing, sitting, throwing, lifting, pushing, pulling, climbing, running, and of course, punching are all quite natural. They got us where we are. They are part of our design. These natural, primal, movements influence the exercises included in CrossFit’s workouts.

– CrossFit Journal March 2004