Watches server a lot more functions than merely keeping time. Modern watches have come to perform a whole lot of functions other than just keep time. They are also programmed to tell the day and date of the year. A lot of them have alarm systems incorporated in them that alerts you at a specific time of the day every day. Some are even designed with a stopwatch.
Broadly, there are two categories of watches, quartz and mechanical watches. While quartz watches work on a battery fitted into the watch system, mechanical watches work on the principle of winding a spring that operates the functionality of the watch. Mechanical watches are manually operated at times, or they may be automatically operated at others. Mechanical watches don't need a battery to run.
While quartz watches are quite accurate when it comes to telling the time, mechanical watches can never be said to be as accurate. Moreover, quartz watches cost much less as compared to the mechanical counterparts. But the inconvenience of having to change the battery once in a while in case of quartz watches is a demerit. This also requires frequent expenditure of money.
Mechanical watches are a bit heavier than their digital counterparts.
The most obvious difference between a mechanical and a quartz watch is obvious when one sees the second hand moving. While a quartz watch has a second-by-second approach to movement, a mechanical watch moves in a sweeping movement over the face of the clock.
While there is a level of craftsmanship considered while making a mechanical clock, this is not to be found in a quartz watch. It derives its power from a battery and requires very less maintenance. They have very few movable parts and so cost a lot less than quartz watches.