Wearable fitness tracking is a massively popular accessory category that helps healthy people keep tabs on their heart rate, how many steps they're taking, how much distance they're crossing, and sleep cycles. This wide range of data is often brought together in smartphone apps and cloud services that offer longitudinal data and boils that information down to useful lifestyle tips based on your activity. This information is usually beamed to the smartphone over Bluetooth 4.0 Low Energy, but ANT+ is another wireless standard that enjoys popularity in the health accessory space. Sometimes smartphones themselves can act as fitness trackers using their built-in accelerometers, GPS units, and in some instances, built-in infrared heart rate sensors.

Though it's most common for health trackers to be worn on the wrist and double as a watch, they can just as often go anywhere: headbands, armbands, anklets and lapel clips are all common form factors. Some are even being integrated directly into clothing. In many cases, the core devices can be switched between various wearable bands, depending on use cases.