A watch is a mechanical timepiece you wear on your wrist.
No. A watch is a piece of jewellery you wear on your wrist. The only difference between a wristwatch on one hand and a pendant, a bracelet or a brooch on the other is that a watch is the only widely allowed jewellery (other than a wedding ring) for men. Of course, the intricate mechanics and technical craftmanship is an added appeal, though the actual function of telling time is just a bonus, not the main point.
And that explains why there are such a large number of watchmakers, and such a huge number of models; with jewellery, the last thing you want is to wear the same thing as everybody else.