Possibly the earliest ancestor of today's robot is the clepsydra, or water clock, which measured time using a flow of water.
Ctesibius of Alexandria, a Greek physicist and inventor, is said to have constructed such a clock about 250 BC.
Today, robots in factories do a lot of the physical labour people used to do.
In car factories, for example, one-armed robots lift, weld, and spray-paint cars. They mimic the movement of a human arm and hand.