Fitbit is a company based out of San Francisco, California United States that focuses on fitness and activity trackers. Many of the trackers are worn on the wrist like a bracelet. However, earlier models like the Fitbit One can clip onto pants or shirt lapels.
The trackers can sync to a Fitbit mobile app found on iOS, Android, Windows, and Windows Phone.
Fitbit trackers keep count of steps taken, length of nightly sleep, floors climbed, and distance traveled. Heart rate monitoring is also available in two models, the Charge HR and Surge. The range or products include the Zip, One, Flex, Charge, Charge HR, and Surge and range in price from $59 to $249. Fitbit also makes a 'smart scale' called Aria for keeping track of your weight (it syncs over Wi-Fi).
Fitbit has become a big supporter of Microsoft products, including Windows Phone and Windows 8.1. The first WInodws Phone app was released in July, 2014 and has had substantive updates over the proceeding months including the addition of Cortana support. The Windows app was also redone to be more than just a reflection of the web site, including supporting direct synchronization of Fitbit trackers.
Despite the competition with the Microsoft Band, Microsoft and Fitbit have a symbiotic relationship. The AT&T Lumia 830 is sold with a free Fitbit Flex and Microsoft often promotes their fitness trackers through the Microsoft Store, which sells them direct.
As of April, 2015, the more advanced Fitbit trackers (Charge, Charge HR, Surge) do not have notification support within Windows Phone for phone calls or alerts. However, updates are expected to enable this feature eventually.