Treading water involves a person staying in a vertical position in the water while keeping his or her head (at least) above the surface of the water. Treading water provides the person an opportunity to keep the head from becoming submerged; since it doesn't provide sufficient thrust to propel the individual in a specific direction, it is used mostly to stay afloat and to conserve energy that might be wasted by trying to swim to another location. Generally, any method used to do this is considered treading water, however, some methods are more efficient than others. Drowning non-swimmers will often splash and kick in an effort to stay above the surface but their lack of technique along with the shortness of breath and panic cause them to tire quickly and not be able to stay above the surface for long. More experienced swimmers often find their own method of staying above the surface. Some methods include sculling and flutterkicking, and other techniques of staying above the surface. The most common method, however, is the eggbeater kick. The eggbeater kick is an efficient way of stay afloat, and allows for use of the hands for things like first aid, rescue, or holding objects. It is the preferred method of treading water, and it's done by alternating rotation of the legs, with one leg rotating clockwise and the other rotating counter-clockwise. The hands may or may not be used to aid the legs.