Pile is a column used to support buildings, bridges, and other structures. Piles are often used to prevent buildings from sinking or collapsing. When the top layers of soil are too soft to support the foundation, piles are used to transfer the weight of the structure to a firmer layer of soil or rock. For some skyscrapers, piles may reach 200 feet (61 meters) below the surface. Piles may also be used to raise a structure above water or to support wharves. Piles may be made of wood, steel, or concrete. They are usually driven into the ground by a pile driver, a kind of hammer that drives the pile into position by means of vibration and a weight. Piles also may be drilled into position or placed into predrilled holes.
