Drill bits are part of the downhole equipment used to dig down into the earth's crust. Like a common hand-held drill, the spinning of the drill bit allows for penetration of even the hardest rock. The drill bit is located at the bottom end of the drill string, and is responsible for actually making contact with the subsurface layers and drilling through them. The drill bit is responsible for breaking up and dislodging rock, sediment, and anything else that may be encountered while drilling.