A machine tool is a powered mechanical device. They are typically used to fabricate metal components of machines by machining which is described as the selective removal of metal. The term machine tool usually refers to those which use a power source other than human movement, but they can also be powered by people if appropriately set up.

Machine tools can be powered from a variety of sources. As aforementioned, human power is an option. However, machine tools evolved and therefore today, most are powered by electricity.  In more recent years, computers have been added to give aid their operation and provide even more flexibility to the process. Such machines became known as computerized numerical control (CNC) machines. These machines could precisely repeat sequences over and over, and therefore could produce much more complex pieces than even the most skilled tool operators.

From the simplest to the most complex, most machine tools are capable of at least partial self-replication since they are machines, and produce machine parts as their primary function.

Examples of machine tools include: lathes, routers, drilling machines, milling machines, grinding machines, circular saws, sanders, hacksaws, table saws, mitre saws and balancing machines.