A fitness tracker is a wearable device designed to monitor and record various physical activities and health metrics. These devices often track steps taken, distance traveled, calories burned, and even heart rate. Many fitness trackers can sync with smartphones, allowing users to view their data through dedicated apps, making it easier to set and achieve fitness goals. In addition to tracking physical activity, some fitness trackers also monitor sleep patterns and provide insights into overall health. Popular brands include Fitbit, Garmin, and Apple Watch, each offering unique features to cater to different fitness levels and preferences.