A machine is a tool that consists of one or more parts, and use senergy to achieve a particular goal. Machines are usually powered by mechanical, chemical, thermal, or electrical means, and are frequently motorized. Historically, a powered tool also required moving parts to classify as a machine; however, the advent of electronics technology has led to the development of powered tools without moving parts that are considered machines.
A simple machine is a device that simply transforms the direction or magnitude of a force, but a large number of more complex machines exist. Examples include vehicles, electronic systems, molecular machines, computers, television, and radio.
Perhaps the first example of a human made device designed to manage power is the hand axe, made by chipping flint to form a wedge. A wedge is a simple machine that transforms lateral force and movement of the tool into a transverse splitting force and movement of the workpiece.
The idea of a “simple machine” originated with the Greek philosopher Archimedes around the 3rd century BC, who studied the “Archimedean” simple machines: lever, pulley, and screw. He discovered the principle of mechanical advantage in the lever. Later Greek philosophers defined the classic five simple machines (excluding the inclined plane) and were able to roughly calculate their mechanical advantage. Heron of Alexandria (ca. 10–75 AD) in his work Mechanics lists five mechanisms that can “set a load in motion”; lever, windlass, pulley, wedge, and screw, and describes their fabrication and uses.