The tourbillon system was made to compensate the Earth’s gravitational force by mounting the escapement in a revolving cage. It gives the watch a better accuracy. This complication is known as one of the most difficult to make.
Watches featuring a moonphase complication display new moons, first quarters, full moons and last quarters.
The power reserve indicator tells you the time the watch will continue to function. It can either be seen on hand winding or automatic watches.