As Facebook counts more than 1.65 billion monthly active users, 1 billion people using Messenger means more than 60 percent of the social network’s users communicate with the app. Messenger is considered the second most popular iOS app, behind Facebook’s main app. People are doing more with Messenger, including making phone calls to friends, colleagues and loved ones, and regularly sending photos, stickers and GIFS to each other. Facebook said more than 17 billion photos are distributed by Messenger each month, with 22 million GIFs shared every day.