FACEBOOK MESSENGER is an instant messaging service and Software Application.Facebook messenger lets facebook users send message to each other.It was launched as a STANDALONE app on the ANDROID and iOS operating systems in AUGUST 2011and the functionality was then removed from the main facebook app in APRIL 2014 .MESSENGER lets users make VIDEO CALLS both in one-to-one interactions and in group conversations.AFTER being separated from the main facebook app, Messenger had 600 Millions users in APRIL 2015, Growing to 900 Millions in JUNE 2016, and reaching 1 BILLION users in JULY.