Facebook is the world's largest social network and one of the most popular apps on Windows Phone. Millions of people use the service daily to connect with friends and family. Users also can chat with their friends using Facebook Messenger, another popular app on Windows Phone.

Facebook was founded in 2004 by Mark Zuckerberg, then a freshman at Harvard. Membership was initially limited to those at Harvard, but later expanded to colleges in the Boston area, universities in the Ivy League, Stanford and then all colleges and universities. Today, anyone can join Facebook, and over one billion people have done that.

You'll find a total of three official Facebook apps on Windows Phone. Facebook, Facebook beta and Facebook Messenger. Facebook and Facebook Beta are developed and published by Microsoft while Messenger is developed and maintained by Facebook.

Facebook bought photo-social network Instagram for $1 billion in 2012. It then bought messaging app WhatsApp for $19 billion in 2014. Both apps are on Windows Phone, but still published under their own name.

Facebook beta gives users an early look at features that will be available in future updates to Facebook. While Facebook Messenger is how users can instant message their connections on Facebook.