Once you have an idea about the style of watch you want, you may want to think about its movement. This determines its accuracy.
The movement operates only when the mainspring is tensioned by the winding of the crown. This power is then slowly released from the mainspring as it unwinds which in turn drives the hands of the watch.
An automatic watch has a movement similar to a mechanical watch, but it 'self winds' using the movement of the wearer. A small pendulum or weight in the back of the watch moving as the wearer moves their arm. As the pendulum moves around an axel, tiny gears transmit this movement to the mainspring. The winder or crown is retained as a feature so that the time and date can be altered manually. (It is worth noting that automatic watches may not be suitable for everyone, as they require enough body movement to generate the power required to wind the mainspring sufficiently and thus maintain the correct time). Mechanical and Automatic movements are generally far less accurate than quartz, losing or gaining anything up to 30 seconds/day.
A module powered by a synthetic crystal, made to oscillate by an electric current supplied by a tiny battery. A very precise and accurate time measurement, usually within + or - 20 seconds/month.
An innovative movement of micro-electronics that responds to the wearer's wrist action to store energy, maintaining quartz accuracy. The watch "sleeps" to conserve energy if not worn for 72 hours but wakes up when shaken and immediately returns to the correct time. Developed by Seiko.
A quartz movement but with a solar panel covering the entire watch face, converts light from any source, whether it is sunlight or artificial light, to electrical energy. With regular exposure to light, the "battery" is constantly recharged, thereby allowing the watch to run continuously. The frequency to which the watch must be exposed to light to maintain accuracy is dependent on the model and capacity of the rechargeable battery.