A hammer drill is a power tool used for drilling into harder materials such as brick, concrete, and stone. It can be used to create holes for mounting hardware, installing wiring, and more. The hammer drill works by using a piston-like mechanism to rapidly strike the bit against the material being drilled. This rapid striking action creates small cracks in the material which enables it to be drilled more easily than a standard drill bit. Hammer drills are especially useful for quickly drilling large numbers of holes in tough materials such as concrete or stone walls.