Traditionally manufactured watches have many internal components that are linked and some of these parts need to be in constant motion to ensure the proper functioning of the clock. The power or the energy that is needed for these parts to be in perpetual motion, used to be provided in the olden day watches with the help of a metal coil. This coil or spring type mechanism would be wound tightly and its natural tendency to slowly set itself right would provide the necessary energy for the other parts to continue their movements. After a while, this coil will lose its stored energy and would have to be rewound again. These types of watches were called manual re-wind watches. These watches need to be rewound on a daily basis otherwise, they would stop working.

Sometime in the recent past, the mechanism for automatic watches was designed and the automatic watches become quite popular because of their ease of use. In these types of watches, the coil mechanism need not be rewound manually; they are designed in such a way that the coil gets automatically rewound due to the natural movement of the hand and wrists. This was a radical discovery in its time and its innovativeness of usage and design are still popular to this day. The coil is loaded onto a semicircular, disc type contraption that is firmly fixed in its center. The movements of the hands will cause this disc to rotate and as a result the coil gets wound automatically. Automatic watches do not need to be rewound on a daily basis and will continue to work as long as they are used. If the watch is not used for a couple of days, the watch will gradually stop working after the expulsion of all the stored energy.

Energy gets stored in the coil spring as long as it is in the wound position. As it gradually sets itself right, the energy gets dissipated. In automatic watches, there is a chance for the coil to get over-wound and expel excess energy as a result. This can cause the watch to run faster or even damage the coil mechanism. To prevent this, all automatic watches have a lock that prevents excess winding. As soon as the threshold is reached, the coil just stops winding itself. Similarly, the release of the coils is controlled, so that even amount of required energy is expelled – nothing more or nothing less. This ensures that the watch movement maintains its timing and displays the correct time, as a result.