Drill bit  For the ficitonal character see Drill Bit
(Transformers).  Drill bits are cutting tools used to create
cylindrical holes. Bits are held in a tool called a drill, which
rotates them and provides axial force to create the hole.
Specialized bits are also available for non-cylindrical-shaped
holes.  This article describes the types of drill bits in terms
of the design of the cutter. The other end of the drill bit, the
shank, is described in the drill bit shank article. Drill bits
come in standard sizes, described in the drill bit sizes
article. A comprehensive drill and tap size chart lists metric
and imperial sized drills alongside the required screw tap
sizes.  The term drill can refer to a drilling machine, or can
refer to a drill bit for use in a drilling machine. In this
article, for clarity, drill bit or bit is used throughout to
refer to a bit for use in a drilling machine, and drill refers
always to a drilling machine.  Metal drills  Twist drill  The
twist drill bit is the type produced in larg