Drowning non-swimmers 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 factor make this a very ineffective method of treading water. They will usually tire quickly and not be able to stay above the surface any longer.
More experienced swimmers often find their own method of staying above the surface. These techniques often involve sculling, flutter kick, and other unofficial techniques of staying above the surface.
The left foot makes a clockwise motion while the right leg makes a counterclockwise motion towards the axis of the body. The legs should never meet because when one foot is on the inside of the motion, the other should be on the outside. The arms are not involved directly in this kick.
Eggbeater kick can be used to move through the water if the body is angled. Because of the opposite motion of the legs, eggbeater is a very smooth and steady way of treading water. It also leaves the hands free to do work if necessary.
This method of treading of water is the preferred method used by lifeguards and other aquatic rescue professionals because of its efficiency and simplicity. The fact that it does not occupy the hands is a major factor in this preference as these professionals often have to perform first aid as they are swimming to safety.
Eggbeater is also used in water polo because it lets the athletes use their arms to throw the ball.