A hammer is a tool that strikes an object to make it move or deform. It is most commonly used to hammer nails, correct or break objects open. Hammers come in a variety of forms. The common form is a handle and a top.
One side of the top is flat for striking, and the other side is the hammer head. The hammer head can be shaped like a sheep horn or wedge, and its function is to pull out nails. There is also a round head hammer.