Diagram of the use of a first-class lever (blue) on a fulcrum (brown)

A lever is a simple machine. It is something that can be used in a lot of ways. One way is by measuring things, or by seeing which weighs more. A lever is supported by a fulcrum which it uses to lifts weights. It is one of six simple machines. There are three types of levers: first-class, second-class and third-class.