There are many different types of watches, from very simple to the most complicated. They may be entirely mechanical, completely electronic, or a blend of both. But the most important feature of any watch is its movement, which measures the passage of time and displays the current time. There are many different movements, but the most common are quartz and automatic.
A quartz watch uses an electronic circuit to drive the display, which shows the time in numeric digits. These are very popular, especially in inexpensive wristwatches. They have a very high accuracy (5 seconds per month) and are very durable.
An automatic watch, on the other hand, uses a complex internal motor made up of springs and gears to move the hands. The way in which this motor is powered divides watches into automatic and manual. Manual, or “hand-wound” watches require the wearer to wind an innerspring by turning a knob on the side of the case; this must be done daily to keep the watch running.
Some watches have special features that make them very useful for specific activities. For example, diving watches are designed to be waterproof and have a special crown for controlling the functions of the watch underwater. There are also watches that indicate the phase of the moon, called a lunar phase complication. Other complications include chronographs and minute repeaters, which add functions to the basic display of the time.
Some watches are specially made for people with visual or hearing impairments. Blind or partially sighted users can use a talking watch, which says the time at the press of a button. There are also watches that use electroluminescent material to produce a uniform illumination of the watch face and hands, making them easy to read in dim light.