====== Walking ====== Walking is the main form of locomotion on land, distinguished from running and crawling. When carried out in shallow waters, it is usually described as wading and when performed over a steeply rising object or an obstacle it becomes scrambling or climbing. The word walking is derived from the Old English //walkan// (to roll). Walking is generally distinguished from [[terminology:running]] in that only one foot at a time leaves contact with the ground: for humans and other bipeds running begins when both feet are off the ground with each step. (This distinction has the status of a formal requirement in competitive walking events, often resulting in disqualification even at the Olympic level.) The average human child achieves independent walking ability between nine and fifteen months old. ----