Garmin Forerunner 255 Smartwatch

Has the ability to connect to a cellular network without a smartphone.

Connects to GPS satellites to measure distance you moved during various exercises without having a smartphone present.

Allows music stored on the watch to be played via headphones without requiring a smartphone.

A short-range wireless technology that triggers a transaction between the watch and another device, usually by bumping them together. On smartwatches, it’s most often used to initiate the pairing sequence with a new phone or tablet to authorize payments at a retailer’s pay terminal.

A long-range wireless communication technology that enables a smartwatch to pair with a smartphone and with other devices within a home network or remote location via the Internet.

An Sp02 blood oxygen sensor measures your blood oxygen level which should be between 95% - 100% for healthy individuals and provides insights into an important indicator of your overall wellness.

Can record your heartbeat and rhythm using the electrical heart sensor and then check the recording for atrial fibrillation, a form of irregular rhythm.

VO2 max refers to how much oxygen your body can absorb and use during exercise. If you’re looking to improve your aerobic fitness, you might consider maximizing your VO2 max (sometimes called your oxygen uptake).

Manufacturer claims their smartwatch can measure blood pressure at-wrist. This is not tested.

A manual method of entering time-of-month data which can be tracked.

Menstrual cycle tracking with temperature uses a temperature sensor to notify that the menstrual cycle has begun.

A coaching method used to guide your breathing in order to reduce stress and is associated with your general wellness.

Stress tracking falls under (Wellness) which is based on various input from sensors for HRV, skin temperature, heart-rate and some others that indicate stress. Different manufacturer's use different algorithms to assess stress levels.

SWOLF is a score that measures your swimming efficiency, and a lower score is better. For pool swimming, the SWOLF score for a length is obtained by adding the number of strokes taken in the pool length, and the time it took to swim that length.

(HRV): High HRV is associated with healthy longevity and the side of the nervous system that promotes relaxation, digestion, sleep and recovery. A low HRV reading is associated with stress, overtraining, inflammation and illness. Diabetes, coronary heart disease and high cholesterol are things commonly tied to having a low HRV as well.

Sleep tracking is the process of monitoring a person's sleep, most often by measuring inactivity and movement.

Alerts you to incoming calls, texts, social network updates, or other notifications by using vibration at wrist or sound or visual.

This is for any kind of map that is shown at-wrist on your watch, either a VISUAL map with streets or some others have only "Navigation" which uses waypoints but shows no visual "underlying" map but just a single route line with no background map.

From the Hansel and Gretel fairy tale by the Brothers Grimm. When their father took them into the woods to abandon them, the children dropped crumbs of bread along the way to leave a trail back home. This is a method of finding your way back to the start of a route. It is very useful if you are lost.

This uses a microphone to detect ambient noise levels. This is not the same as headphone noise level protection.

Crash Detection uses sensors and algorithms that detect severe car crashes and automatically contact emergency services. This is not tested.

Emergency SOS on some watches is enabled by pressing and holding a side button to quickly contact emergency services and provide them with your location. For a period of time, your emergency contacts will get updates when your location changes. This includes 911 calling. This is not tested - it is claimed.

Fall Detection or Incident detection is used if you’re at home or out adventuring, if a fall is detected and you’re unresponsive, a call to emergency services will be placed automatically.

One watch can provide an 86-decibel siren. If you get lost or injured and need to attract attention, an 86 dB siren can be heard up to 600 feet or 180 meters away.

A low battery indicator is shown on the watch screen.

Some smartwatches have displays that are "Always-on" and some can be switched to "Always-on".

Indicates whether the watch can be controlled by touching its display.

Technology used by the display, such as OLED, AMOLED, Super AMOLED, LCD, or e-paper.

Indicates what type of heart-rate monitor is used, if at all. The two main types are active and stationary. Stationary heart-rate monitors measure your pulse only at intervals you choose, mostly at rest. Active heart-rate monitors measure your pulse continuously, or automatically at variable intervals.

Claimed number days, often a range, manufacturer says the watch will function on a charge.

Indicates which phones, either specific models or the operating system they use that works with the watch.

How resistant the watch is to submersion in water, as tested by subjecting the device to a water pressure equivalent to the depth the manufacturer claims the smartwatch can withstand.

The material used to protect the display. Often it’s made of a mineral such as sapphire or quartz, or other materials such as glass or plastic.

Primary material used to manufacture the case, excluding the display.

The diameter of the case, measured to nearest tenth of an inch.

Size of the active screen, to the nearest tenth of an inch.

Weight of watch in ounces.

Thickness of the watch measured to the nearest tenth of an inch.