Most people think of a machine as a large and noisy invention with lots of moving parts, that runs on electricity or gasoline. Actually, a machine is anything that makes work easier to do.

A machine helps you do work. It transfers energy from one place to another or transforms it from one form to another, to make work easier. A machine puts force where you want it to go and where it gives you the greatest help.

There are two types of machines: simple machines and complex machines.

A simple machine is any device that only requires the application of a single force to work. Examples include a lever, a pulley, or a wedge, . You may not have thought of these things as machines before, but they are all tools to make work easier. A complex machine is several simple machines put together. When you think of machines such as engines, you are thinking of complex machines. When a machine is used, some outside force does work on the machine. The machine then delivers work to something on which it acts. Have you ever used a stick to write or draw in the sand? That stick is a complex machine, taking the force of your muscles and applying it to the sand through the stick.