A machine is a tool used to make work easier. Simple machines are simple tools used to make work easier.
Compound machines have two or more simple machines working together to make work easier.
In science, work is defined as a force acting on an object to move it across a distance. Pushing, pulling, and lifting are common forms of work. Furniture movers do work when they move boxes. Gardeners do work when they pull weeds. Children do work when they go up and down on a see-saw.