Battery which can be recharged by an external energy source.

This term refers to a watch with a mechanical movement. The internal rotor (part of the automatic mechanism) winds the mainspring by the motion of the wearer’s wrist. If an automatic watch is not worn for a longer period, it will wind down and stop working.

This is essentially an oscillator which regulates the running speed of a mechanical watch.

A bezel that can be turned either clockwise or counter clockwise. Rotating bezels can be used to measure elapsed times or read second or third time zones.

A feature that shows the date. Day, month, and moon-phases are often shown additionally. There are several types of calendar watches. Most calendar watches show the information digitally through an aperture on the watch face and some watches show the information on sub-dials.

A watch case has several parts. The bezel (which holds the crystal), the case middle part (which contains the movement and fitted the strap/bracelet) and the case back which is either snapped or screwed on.

A chronograph is a mechanism for measuring short time periods independently of the normal timekeeping function.

Contrôle Officiel Suisse des Chronomètres (Official Swiss Chronometer Testing Institute)

A function that lets the wearer keep track of how much of a pre-set period of time has elapsed. Some countdown timers sound a warning signal a few seconds before the time runs out.

The crystal is the transparent cover over the dial. There are various materials used like plastic, mineral glass or sapphire.

The date is showing through an aperture in the dial. Typically at the 3 o’clock or 6 o’clock position

The face of a watch showing the time and other functions that may be displayed by hands, markers, discs or through windows.

Some battery operated watches have a feature that indicates when the battery is approaching the end of its life. This is indicated by the second hand jumping every 4 seconds or in a digital watch, by a flashing display.

Number of oscillations per second, expressed in hertz (Hz). A watch with a count of 36’000 vibrations per hour (18’000 oscillations), in 1 hour (3’600 seconds), has a frequency of 5 Hz. Thus a watch beating at an frequency of 36’600 per hour ticks 10 times per second.

A GMT watch has a second hour hand (or a disc) which completes one full rotation in 24 hours. On the dial or bezel is a 24-hour index (or an arrow for the disc) to read the second time zone.

Indicator, usually made of a thin, light piece of metal which moves over a dial. Very variable in form.

Unit of frequency. The frequency of the quartz resonator is 32’768 Hz. Mechanical watches have a frequency of 2.5 to 4 Hz.

A watch bracelet that is incorporated into the design of the case.

A digital watch display that shows the time electronically by means of a liquid held in a thin layer between two transparent plates.

A movement which has only mechanical parts and is powered by a mainspring and working in conjunction with a balance wheel. The mainspring must be wound manually.

A movement usually battery powered, which uses an electric current to cause a quartz oscillator to vibrate, normally 32’768 Hz per second.

In an automatically winding wristwatch, the rotor is winding the mainspring by the movements of the wrist. It is a segment made of heavy metal, which turns freely in both directions.

A crown that can be screwed into the tube of the case to make the watch highly water resistant.

A hand which showing the seconds on a sub-dial.

Describes the level of protection a watch has from water damage.