Overview#Facebook Messenger is an Instant Messaging (IM) service and software application.
Originally developed as Facebook Chat in 2008, the Facebook revamped its Instant Messaging service in 2010, and subsequently released standalone iOS and Android apps in August 2011. Over the years, Facebook has released new Facebook Messenger applications on a variety of different Operating Systems, launched a dedicated Facebook Messenger website interface, and separated the Facebook Messenger functionality from the main Facebook app, requiring users to use the web interface or download one of the standalone apps.
Users can send messages and exchange photos, videos, stickers, audio, and files, as well as react to other users' messages and interact with chatbots. The service also supports voice and video calling. The standalone apps support using multiple accounts, conversations with optional end-to-end Encryption, and playing games.
After being separated from the main Facebook app, Facebook Messenger had 600 million users in April 2015, growing to 900 million in June 2016, 1 billion in July 2016, and 1.2 billion in April 2017.