Having a watch that’s “complicated” sounds daunting and undesirable if you are not familiar with the term. However, watch complications are actually highly desirable and can simplify and enhance your life.

The term complicated, when it refers to watches, indicates special functions that the watch is able to perform and display. An example of a complication is a moon phase display. Watches that show only the hours, minutes, and seconds have so-called simple movements.

Collectors prize their complicated watches because they display useful information. Perhaps more importantly, a collector appreciates the innovation, skill, and ingenuity that watch complications represent. We are all familiar with battery-operated digital watches that have myriad functions. However the watchmaker’s complicated watch functions completely mechanically, without a computer chip full of data, or a battery.

Some complicated watches can display the date accurately (including leap years), until 2100 and beyond. Other complicated watches can also chime the hour, quarter hour, and minutes,  have a stop watch accurate to 1/10 of a second, and display the moon phase. There’s even a complication called the equation of time, which shows the exact solar length of the particular day (only 4 days a year are exactly 24 hours long).

A “quartz” watch that has a battery can also have many functions, but they are simply called functions and not complications.

A list of watch complications and a brief explanation of their functions

Alarm Watch –a watch with a built in chimethat can be set to ring at a specific time.

Annual Calendar – a watch that automatically adjusts between 30 day and 31 day months throughout the year. It must be readjusted in February.

Automatic Watch – a watch that winds itself with the movement of the wearer’s wrist, usually accomplished with a rotating “rotor” disc that turns and winds the watch.

Chronograph – a watch that has a timer function, indicating seconds and sometimes sub-seconds, minutes, and hours.

Double Chronograph or Rattrapante – a split-second timer or lap timer that usually has two hands for the “split” time.

Dual (or Multiple) Time Zone – A dual time zone displays the time simultaneously in two zones, often indicated by two hour hands, or a sub dial. Multiple time zone watches have additional sub dials, hour hands, or 24 hour indicators on the bezel of the watch.

Equation of Time –  the actual solar length of most days of the year is not exactly 24 hours and zero minutes. In fact the solar time varies by as much as 16 minutes shorter and 14 minutes longer. This complication shows the equation of time (the addition or subtraction of minutes for the day).

Flyback Chronograph – while the chronograph timer is running, it can instantly be reset, without first stopping the motion, resetting,  and then starting it again.

GMT – a watch that displays Greenwich Mean Time as well as your home time. Can also be used as a dual time zone watch.

Leap Year – a watch that displays successive years as  1, 2, 3 and 4, with 4 indicating the leap year. These watches almost always also feature a perpetual calendar.

Minute Repeater – a watch that can chime the hours, quarter hours, and minutes on demand with the push of a button or the pull of a lever. The minute repeater has small hammers that strike tiny gongs which create different tones for the minutes, hours and quarter hours. Minute repeater watches were very useful before electricity. They also had a great value for soldiers in the field at night who needed accurate timing but could not see their watches.

Moonphase – a sub-dial displaying the phase of the moon. This early complication was especially useful for night travelers who needed the light of the moon to help find their way.

Perpetual Calendar – a function that shows the day, month, date and year. It adjusts automatically for February and leap years without needing to be reset, usually until 2100.

Power Reserve Indicator – This complication tells the wearer instantly via a sub dial or linear indicator how much time is left before the watch will stop. It’s very useful for automatic watches. It’s also enjoyable to see the indicator rise slowly as the movement of your wrist winds the watch.

Tourbillon – a small rotating cage that houses the balance, hairspring and escapement. The rotation of the tourbillon effectively eliminates the pull of gravity on the accuracy of the watch.

World Time – This function allows a watch to simultaneously display the time in multiple time zones. Most world timers display 24 time zones, with each zone indicated by the name of a major city in that zone.

Here a image gallery with some great examples of watch complications