A pumpjack is a mechanical device used to extract oil from underground reservoirs. It operates by converting the rotary motion of an electric motor into a reciprocating motion, which drives a piston in a well. This process helps bring crude oil to the surface, making it an essential component in the oil extraction industry. Typically seen in oil fields, a pumpjack consists of a long arm that moves up and down, often referred to as a "walking beam." The device is also known as a nodding donkey or horsehead pump, and it plays a crucial role in the overall production of crude oil.