Facebook has announced a new feather M for Messenger. M is a digital personal assistant build into Messenger. It can your independently for you like a personal assistant for you such as buy things, make travel arrangement, make restaurant reservations, buy ticket, hotel booking, deliver gift to someone you want or just anything else you ask it to do.
Facebook has introduced this new feather when Apple has Siri, Microsoft has Cortana and Google has Google Now. Though they are providing likely same service with limitation, but M has came with bigger way. If you thing about Siri and Google Now; they only can provide rote answer and reminders.
Facebook is not thinking to monetize M directly. Using ads on messenger can be a big opportunity for Facebook to earn cash by giving personal assistance service to user.