Simple machine

A simple machine is a device that can change the direction or the magnitude of a force, or the point where it is applied. This is done so that the force can be used to do work. All mechanical machines are made by combining simple machines.
There are six basic "simple machines", as defined by Renaissance scientists: 
The use of simple machines can be traced back to "homo habilis" (the first humans to use tools), but certain animals other than man also use them. 
A "compound machine" is made up of two or more simple machines.