A device within a watch that allows one to measure altitude by identifying changes in barometric pressure. This is considered essential for climbers, aviators, mountaineers, etc.

A watch display that shows the time with the help of the hour and minute hands.

A watch unaffected by changes in the magnetic field.

It refers to a watch that doesn't need the user to manually wind it for use. It contains an additional weighted pendulum known as the rotor, which spins and automatically winds the watch while it is in motion. The user needs to wind it manually in case it is not worn for more than a couple of days.

A small window-like opening within the dial of the watch that displays information such as the date, month, or day of the week.

A feature that helps the user identify whether the indicated time is AM or PM i.e., day or night.

A timer designed with the function of resetting itself once the preset time has elapsed. An auto repeat countdown timer keeps repeating unless it is manually stopped by the user.

A weighted wheel found in mechanical watches that oscillates continuously, dividing time into equal parts. The to and fro movement allows the hands to move forward, thereby ensuring accurate time.

The cylindrical part of the watch that contains the mainspring. The power reserve of the watch depends on the size of the barrel. Adding additional barrels can expand the power reserve.

The ring-like structure present on top of the watch that holds the crystal in place. It is usually made of metals like gold, stainless steel, silver, etc., and it helps in measuring time increments. Bezels can be of different types such as fixed, uni-directional, bi-directional, etc. In rare cases, the bezel may also be located below the crystal.

A bi-directional rotating bezel can be turned in both clockwise and anti-clockwise directions. It helps in keeping track of the elapsed time.

The metal strap that allows the user to wear the watch on their wrist. It is usually made of separate links that allow the wearer to adjust the length according to the size of the wrist.

The part of a mechanical watch that is fixed to the mainplate to form the frame housing the inner workings.

The term caliber or calibre is used to differentiate the various types of watch movements.

Refers to a slightly convex crystal.

The housing that encases all the parts of the watch. It is usually made of metals like stainless steel, gold, or silver and it comes in a variety of shapes.

The reverse side of the watch’s case that lies on the wrist. It can be removed to access the inner parts of the watch.

A watch that measures time with high accuracy. In order for a watch to be identified as a chronometer, it needs to undergo stringent tests by the Swiss laboratory C.O.S.C. or Controle Officiel Suisse des Chronometres. According to the standard procedure, the performance of the watch is measured for a period of 15 days at 5 different positions and 3 temperatures.

This function of the watch allows one to know how much of a pre-set time period has elapsed. This is especially useful for athletes.

Any additional feature of a watch apart from showing the time. Watches with more complications are usually more expensive.

The tiny knob or button on the side of the watch case. It is used to adjust the time, day, or date depending on the type of the watch. It is also used for winding the movement to power a mechanical watch.

The transparent protective cover on the watch face. A watch crystal may be made of different materials such as glass, plastic, mineral crystal, synthetic sapphire, etc.

A watch that shows both the date and the day of the week.

Also called the AM/PM indicator, it helps in identifying whether it is day or night in other time zones. Usually found in Dual Time Display or World Time Display watches.

It is an expandable buckle attached to both sides of the watch strap that fastens by folding over itself. Invented in 1910 by Louis Cartier, it offers more security as the watch stays on the wrist even when the buckle is open. It also elongates the life of the strap by reducing the strain on it.

It is the face of the watch showing the time and date. It usually consists of a metal base and is covered with a transparent crystal for visibility.

A watch that shows the time in digits, instead of hands and dial. These are usually LCD watches.

A watch that shows the time using both numerical digits and the hour and minute hands. It is also known as AnaDigi (Analog and Digital) display.

A rotating bezel with markings used for keeping track of the elapsed time. It allows the user to align the bezel with the minute or seconds hand to make reading the elapsed time easier.

It is a linkage found in mechanical watches that controls its motion. The ticking sound of the watch is due to the escapement.

Chronographs contain an extra seconds hand that can be stopped by the user and then made to fly back to the actual seconds hand with the press of a button.

This refers to the speed of the ticking of a watch. It is usually measured in hertz or vibrations per hour.

It is used to denote the numerous tasks that a watch is capable of performing. It is also known as a complication.

This feature is usually found in water-resistant watches. It is a ring made of rubber or plastic that is used to seal the gaps in the case-back, crystal, and crown to block water or dust from entering the watch.

It is the system of gears that helps in transmitting power from the watch’s mainspring to its escapement.

It is an alloy of copper, nickel, and zinc, and may sometimes contain small amounts of lead or tin. This material is extensively used for making watches due to its toughness and corrosion-resistant properties.

It is a method of depositing a very thin layer of gold over another metal surface. The thickness of gold plating is measured in microns.

It is the standard by which all the time zones of the world are set. GMT watches usually show two time zones at once.

Engine turning or guilloche is a method of engraving that is often used to decorate watch dials. It consists of intricately designed repetitive patterns etched precisely on a metal surface.

This is used to refer to the indicators on the dial that point to the hour, minutes, and seconds, allowing the user to read the time. These can vary in their shape.

Also known as balance spring, this is an extremely fine spring that helps recoil the balance wheel of a mechanical watch. Its length regulates the timekeeping of the watch.

Professional divers spend a considerable period of time in highly pressurized enclosures like diving bells. They come in contact with helium molecules that are tiny enough to enter the interior of the watch. While this does not pose a problem underwater, the helium is not able to escape from the watch even on the surface. And this can cause the watch crystal to pop up and separate from the dial.

As a remedy, high end professional diving watches come with a helium escape valve that allows the helium to escape. This is a one-way valve that allows the gas to escape while also preventing water from entering the watch.

Horology is the science of the measurement of time.

The markings (numerals, symbols, etc.) denoting the hours in a watch.

The stick or line-like markings on the dial of an analog watch that are used to represent the hours instead of Arabic or Roman numerals.

This is one of the most popular shock absorption systems built into watches.

Synthetic gems (usually sapphires or rubies) that are used as bearings for the watch’s gears to reduce friction and prolong its lifespan. It helps increase the accuracy of movement.

A feature that shows the hour using numerals on an aperture on the dial. The underlying mechanism causes the display to jump to the next numeral when each hour is up.

A finishing technique that consists of a pattern of straight or curved lines. It makes the surface grippier.

This is a feature in a chronograph that allows one to time segment during an event or race.

Liquid Crystal Display or LCD watches show the time in numerals with the help of a layer of liquid stored between transparent plates.

Lugs are the projections at both ends of the watch case where the strap is attached. These help to hold the strap in place.

It is the property of glowing in the dark. Several watches come with luminescent hands or markers to make it easy to read the time at night or in dimly lit environments.

It is a substance that helps keep all the small parts within a watch moving freely and easily.

The base plate of a mechanical  watch that houses all the other parts.

It is a coiled spring situated within the barrel of the watch. It provides power to a mechanical watch.

This is a watch that requires a user to manually wind the watch for regular use. Once it is wound, the watch remains functional for a specified period of time, post which the user will need to re-wind it.

This feature allows users to convert one type of measurement into another.

A watch running on mechanical movement consists of several small parts including screws, springs, and gears. It is operated by either manual or automatic winding.

A type of glass used in case backs. These are usually less scratch-resistant than sapphire crystal.

A minute repeater is a watch function that can sound the hours or minutes in the form of gongs. This feature is generally found in high-end watches.

A watch that displays the phases of the moon over its 29 and a half day cycle.

It is the outer coating of pearl, often used for crafting the dials of high end watches.

The inner working mechanism of the watch is known as its movement. It can either be mechanical or battery operated (quartz).

The numbers (either Arabic or Roman) used to denote the hours, minutes, or seconds within the dial.

It is the rhythmic back and forth movement within a watch.

This is a technique of making cloud-like decorations on the bridges and plates of a watch. It is also known as circular graining.

It is a feature that shows the day, month, year, moonphase and leap year. Watches with this complication come with the ability to automatically adjust to the varying lengths of months, thereby displaying the correct date even during leap years.

A coating of one metal over another metal surface. Watches are usually plated with gold, silver or platinum.

A very rare metal used for making watches. It is white, lustrous, exceptionally strong, and resistant to discoloration.

This is a feature that shows the power remaining in a mechanical watch. The watch will need to be wound again when the power reserve runs out.

A scale present in a watch that allows one to measure their pulse rate.

A process that enables the watch to attain a smooth and shiny surface. It enhances the look of the finished product.

A button that helps start a function of a watch like setting an alarm or changing the date.

PVD or physical vapor deposition is a technique used for adding color to a watch case to enhance its appeal.

It is a material that generates an electric charge on the application of mechanical pressure. These battery operated watches show more accurate timings and are less expensive.

It is the watch movement that is powered by quartz crystals.

A regulator display consists of separate axial and sub dials for the minute and hour hands. This makes viewing the time easier.

The balance wheel and balance spring of a watch are known as its regulating organs.

It is a watch complication that rings the time on pressing a side lever.

Retrograde display shows the functions of the watch in a linear instead of a circular fashion.

It is a part present in automatic watches that constantly rotates to wind the mainspring.

A watch bezel that can be rotated in one or both directions.

A material that is several times harder than mineral glass. These are extremely resistant to scratches but may crack or shatter on an impact due to their brittle nature.

Watches that are designed with a back case that can be screwed in to cover the internal parts.

A crown that can be screwed down tightly to the case to prevent water and dust from getting in. This is an essential feature for diving watches.

A system built into a watch for absorbing shocks to protect the delicate parts from damage.

The ability of a watch to resist shocks and impacts without sustaining any damage, even on being dropped.

A common material used to make watch parts. It is resistant to magnetism.

A rust-resistant durable material used for creating watch cases and bracelets.

The strip that helps attach the watch to the wrist. It is usually made from leather or rubber. A metal strap is referred to as a bracelet.

A smaller dial present within the main dial. It is used to provide additional information.

It refers to the 24 divisions of the globe, each with a different time.

It is a watch mechanism that is used for tracking and displaying the elapsed time, usually on a sub dial.

A substance with tiny radioactive properties used for making the hour or minute hands luminescent.

A bezel that can be rotated in a single direction (usually counter clockwise) to measure the elapsed time.

A movement caused by oscillation within the watch

 The ability of a watch to resist damage when it comes in contact with water. Diving watches usually mention the depth till which the device is water resistant.

The strap or bracelet that enables the user to attach the watch to their wrist. It can be made from metal, rubber, leather, etc.

A non-metal watch band.

Tightening the mainspring of a mechanical watch is known as winding.

It is created by alloying gold with nickel or palladium to achieve a whitish color. White gold is a popular material for designing high-end watches.

A watch designed with a dial that can show the time of all the 24 time zones around the world.

The most popular color of gold used for constructing or plating on watches.