The history of watches began in 16th-century Europe, where watches evolved from portable spring-driven clocks, which first appeared in the 15th century. The watch was developed by inventors and engineers from the 16th century to the mid-20th century as a mechanical device, powered by winding a mainspring which turned gears and then moved the hands; it kept time with a rotating balance wheel. In the 1960s the invention of the quartz watch which ran on electricity and kept time with a vibrating quartz crystal, proved a radical departure for the watchmaking industry. During the 1980s quartz watches took over the market from mechanical watches, a process referred to as the "quartz crisis". Although mechanical watches still sell in the watch market, the vast majority of watches as of 2020 have