An activity tracker, also known as a fitness tracker
such as distance walked or run, calorie consumption, and in some cases heartbeat and quality of sleep.
It is a type of wearable computer. The term is now primarily used for smartwatches that are synced, in many cases wirelessly, to a computer or smartphone for long-term data tracking.
There are also independent mobile and Facebook apps. Some evidence has found that the use of these type of devices results in less weight loss rather than more.