Fitbit is a small device that accurately tracks your calories burned, steps taken, distance traveled and sleep quality. The Fitbit contains a 3D motion sensor like the one found in the Nintendo Wii. It tracks your motion in three dimensions and converts this into useful information about your daily activities. You can wear the Fitbit on your waist, in your pocket or on undergarments. At night, you can wear the Fitbit clipped to the included wristband in order to track your sleep.