This is the second generation of step counters from Jawbone. It communicates via bluetooth with an app on your phone to track your steps and sleep. You can also log meals and exercise. The app has various settings to help you reach goals (i.e. weightloss, activity, water intake etc.). You can also set it to vibrate after a certain time has passed if you haven't been active. There is also an alarm function that tries to wake you up at an ideal time in your sleep cycle, but I found I needed more than a light vibration on my wrist to wake me up in the morning! It is pretty accurate in judging your activity. I find that it's a good motivator and I like the design of it. It looks more like a bracelet than other brands of activity trackers.