In a last November Facebook has announced about the coming Facebook app chat messenger (a trial version) that could only accessed by some people, and now this chat app messenger really has been officially launched by Facebook globally to public enable to download which is this chat app messenger supports for your Windows OS.
Eventhough Facebook chat messenger isn't something new for you, it means that you still could access them with Non-Facebook chat app such as Yahoo messenger, Live Messenger, Adium, and more that support with Facebook chat intergration, but with this launching it is indicated that Facebook really serious to give totally best services for the users.
With this new chat app messeger, it's allowing you to access your Facebook account to chat with your friends without you have to login to www.facebook.com, which it's said by Facebook on Facebook Help Center:
You can chat and messege your friends on Facebook
You are enable to see the latest updated from your friends in ticker
You still can see the notification about what's going on
You can just simply download Facebook FB chat messenger app for you Windows below.
Download Facebook App Chat Messenger | Binary File (482 KB)