Drilling is the process of forming holes in steel and other materials utilizing a drill bit. This can be achieved by using either carbide single point, carbide multipoint, or high-speed steel bits. The material is cooled using coolant from a reservoir in the drilling machine. This coolant also blows away the chips as they emerge from the hole ensuring a smooth finish.
A counterbore is a flat bottomed hole that enlarges an existing hole. It is typically used when a fastener is to be used on a workpiece, the head of which must be either flush with or below the surface of the workpiece.
Reaming is a process that enlarges a pre-existing hole, usually drilled, utilizing a special reaming tool. This ensures a closer tolerance hole than can be achieved by drilling alone.
Tapping is a process that forms threads in a drilled or reamed hole, usually for screws or bolts. The tool used for this process is called a tap.