A watch movement is the guts that keep your designer watch for men from being just a piece of jewelry and allows it to maintain accurate time. The first watches and timepieces utilized huge weights or required manual winding to power the movements, and these methods were to large to power a small watch worn on the wrist!
Earlier watches were limited to a couple of mechanical arms, didn't illuminate in the dark and didn't include a stop watch function or keep time in multiple time zones. But a lot of these features are included in the modern designer watch for men and the current level of miniaturization allows them to still utilize some form of the automatic movement that has been a classic method of timekeeping for more then a century. And they are loved by those who appreciate history and fine mechanical design!
An automatic movement is made from gears and springs, a spring when wound stores energy and this energy powers the gears which keep time. Automatic watches keep the spring wound by utilizing a mechanism which winds the spring a tiny amount whenever there is movement of the wrist. No more broken springs from over winding!
You have probably seen the adds where the specifications state that the designer watch has a jeweled watch movement. This refers to the gears of the watch which are crafted from synthetic jewels. Once upon a time real jewels were used but due to the cost were replaced by man made ones. Four to forty jeweled gears may be utilized in today's complicated watches. Jeweled gears are used because they generate less friction then metal gears and so require less effort to turn them and this keeps your designer watch running longer.
The quartz movement will keep time to tenth of a second daily while the mechanical movement will only maintain an accuracy of several seconds. So why do people still buy watches with mechanical movements? Simple, some people just appreciate fine mechanics and nothing shows them off more then a fine mechanical watch. And these mechanical watches can last for generations, they never need to have batteries changed and when you wear one you know you have a fine watch on your wrist!