Facebook Messenger is an app that lets you send messages to your friends for free, Facebook Messenger which has been on Androi and ios and has witnessed various updates is now available for the Windows Phone platform.
Some of these features are already built into the Windows Phone platform, but with this release, Microsoft will replace that functionality with the Facebook Messenger app. We’re likely to see those changes in the upcoming Windows Phone 8.1 update, which should be arriving in April 2014.
You can download Facebook Messenger for Windows Phone here.