Facebook Messenger M is a new artificial intelligence feature designed to make the messaging app "more useful, seamless and delightful." At least that's how Facebook puts it anyway. What M does is offer suggestions based on the conversation you're having. For example: If payment is being talked about then an option to transfer money will pop up. Should the group chat be in turmoil over what restaurant to eat at Facebook Messenger M will suggest conducting a poll.
You'll know when M is active as a small icon with the letter will appear in the Messenger chat box. Facebook Messenger M can be disabled if users get sick of constantly fielding suggestions from the A.I.-powered bot. However, you may want to leave it active as the company says M learns your preferences and tendencies the more you use it. For now Facebook Messenger M is only available to those in the U.S., although a global roll out is planned.