An important technology in allowing people do to work was the invention of the gear, a system consisting of cogs that takes energy from an input source, such as flowing water, and convert it to an output source, such as a pump. The oldest archeological evidence for gears dates to about 230 BCE in China, however evidence of geared technology before that time is referenced from ancient manuscripts.
There are various different types of gears such as spur gears, bevel gears and worm gears, with each type providing a unique set of advantages and disadvantages. For example bevel gears change the axis of rotation (such as from horizontal to vertical) and spur gears may change the speed of force of motion.
The earliest gears were uses in wheels and pulling systems and its uses have since expanded dramatically. Clocks, vehicles, and a multitude of machines would not be able to operate with out properly working gears.