Annual Calendar: A watch that automatically adjusts months with 30 or 31 days, requiring only a single manual correction a year, at the end of February.

Arabic Numerals: When the hours on the dial are marked with Arabic numbers 1, 2, 3, etc.

Automatic Movement: A mechanical movement with a rotor that moves with the motion of the wrist and winds automatically the mainspring.

Bezel: A ring that retains the crystal over the dial

Case: The metal casing that encloses and protects all parts of the watch. It is usually made by stainless steel, gold, platinum, or titanium.

Chronograph: A watch that combines both timekeeping and stopwatch functions meaning that it can be started to time a given event and then stopped and returned to zero. Some chronographs (split seconds) can time more than one event at a time.

Chronometer: A watch whose mechanism has been tested by a neutral organization (not by its manufacturer) in different temperatures and positions for a period of time, in order to meet certain precision standards. In Switzerland only the watches certified by COSC (Controle Officiel Suisse des Chronometres) may use the term chronograph. Complication: A watch with additional functions to the normal timekeeping. For example chronograph, minute repeater, tourbillon, perpetual calendar, or split second. The more "complicated" the timepiece, the more valuable it becomes.

Crown: Button on the outside of the case that is used to wind the watch and set the time and the calendar. In water resistant watches, the crown should screw down.

Deployment Buckle: A type of buckle attached to a leather strap similar to a bracelet that makes safer and more comfortable to put on and remove the watch.

Dial: The watch "face". A thin disc or plate, usually made of metal or another material, where the hours and others functions are indicated.
Dual time zone: A "traveler's watch that measures two times simultaneously. Home time and an additional time zone. Also called second time zone or GMT.

Fly Back: A function initially used by pilots that allows the chronograph to be reset to zero and start again pushing the button only once. ("Retour en Vol" in French).

Geneva seal: ("Poincon De Geneve"in French) It is a distinctive hallmark with the symbol of Geneva, granted to a watch movement that fulfills certain criteria set by the Ecole de Horlogerie de Geneve. It is reserved only for movements made in the Canton of Geneva.

Hands: The pointing markers made of thin metal, that circle around the dial indicating the hours, minutes, seconds etc.

Hand wound: A mechanical watch that is wound by hand using the crown. It is also called "manual movement"

Haute Horlogerie: Literally "High Horology" in French. A term that refers to the very high quality watch making.

Jewels: Synthetic rubies or sapphires used to reduce friction in the mechanism Watch movements usually have 15 to 21 jewels.

Jumping hour: When the hour is displayed through a small window ("aperture") and changes (jumps) every 60 minutes.

Manufacture: Refers to a watch manufacturer, that produces in house all the major parts and components of a watch instead of just assembling parts acquired from other manufacturers.

Minute Repeater: A complication that can "sound" time in hours, quarters, or minutes at request by pushing a button. It's initial purpose was to be able to know time in the dark. It is called 'Grande Sonnerie" when the hours and quarters sound (chime) automatically and by request. Moon Phase: (also Lunar Phase) Indicates on the dial the evolution of the lunar cycle.

Movement: The inner mechanism of watch that keeps time and moves the watch's hand, calendar, etc.

Power Reserve indicator: ("Reserve de Marche"in French) A feature on the dial that shows the remaining amount of winding left in the mainspring or for how long the watch will operate before needing to winding it again.

Perpetual Calendar: A watch that automatically adjusts and displays the date 'perpetually', taking into account the varying lengths of the months and leap year's.

Retrograde: When a "hand", instead of making the standard circular move around the dial (or a sub counter), only completes half circle or less and suddenly snaps back to its initial position and starts again.

Rotor: A half disk made of heavy metal, that turns freely in both directions with the movement of the wrist, winding the movement's main spring.
Sapphire Crystal: (synthetic corundum) A scratch-resistant man-made substance used for watch crystals.

Self winding movement: See automatic movement.

Skeleton Case: A case with a transparent front or back that makes visible all main parts of the watch's movement.

Small Seconds: A small sub counter that indicates seconds (instead of a large sweep seconds hand) placed usually near six o'clock on the dial. (Also nine o'clock for some manufacturers).

Sweep Seconds-Hand: A seconds-hand that is mounted in the center of the watch together with the hour and minutes hands.

Tonneau shape: A barrel shaped watch case, first introduced during the "Belle Epoque"

Tourbillon: A device (type of escapement mounted in a revolving case) invented in 1795 by Abraham Louis Breguet that compensates the effects of gravity when a watch is in vertical position. Today's mechanical timepieces do not require its use in order to be accurate. However due to the highly specialized skills that are necessary to make a tourbilIon and its complex structure it is one of the most valued mechanisms in a watch.

Vallee De Joux: A valley situated in the Jura region, considered the "soul" of Swiss watch making. During the long winters the inhabitants worked indoors, and exceled producing watch parts in small workshops. Brands like Audemars Piguet and Jaeger-LeCoultre operate in the area, since their establishment, being guardians of century's old tradition.

World Time: A watch with a sub dial around the main dial indicating the local time in different time zones around the world. In the sub dial appear the major cities of every particular time zone.