A watch function other than telling the time is a known as a complication. A watch that just indicates hours, minutes and seconds is said to be 'simple'. A watch with other functions is 'complicated'. A watches with three or more complications is known as a 'grand complication'.

The most basic complication is acalendar, which may just have the day number. More complicated calendars show the day, date and month or may be a perpetual calendar which takes into account the varying number of days in a month and leap years.

A popular complication is a chronograph - a watch that possesses a stop watch and comes in many forms to measure everything from miles per hour to pulse rate. Other coveted complications include tachymetertourbillion and minute repeater.

A complication or function that is increasing in popularity is moonphase. A moonphase watch provides a reminder of watchmaking's ancient links to astronomy. It visually displays the phases of the moon, day, month and date. It's the revival of moonphase watches that has rekindled the recent interest in mechanical watches.

When you're choosing a watch, have a think about which functions you need. If you're an avid pilot, you'll want an altimeter - a function that responds to changes in barometric pressure to provide altitude. If diving's your thing, you'll be looking for a watch with at least 200 metres water resistancy. Our glossary of watch terms will help you understand the many watch functions available today.