Hi,
A machine is any device that makes work easier by changing a force . It can increase the strength of force , increase the distance over which force is applied or change the direction in which force is applied .

A simple machine uses a single applied force to do work against a single load force. Ignoring friction losses, the work done on the load is equal to the work done by the applied force. The machine can increase the amount of the output force, at the cost of a proportional decrease in the distance moved by the load.
Hope it helps...