Complication accepted to name any function of a watch beyond basic timekeeping. Nowadays there is a great amount of them. Some of complications are more useful, some of them are only for aesthetic pleasure. Watches that include complications are called «complicated watches» and may be divided in three basic categories:
Watches that are endowed with complications from all three categories are called «grand complication».
The most popular watch complications that are most often found in majority of high-end models are tourbillon, repeater, different types of calendars and date complications, moon phase indicator and tachymeter.