Facebook has rolled out end-to-end encryption for all 900 million Messenger users so your conversations can’t be monitored by third parties. However, the new feature isn’t as usable as it needs to be.
You’ll need to manually enable the ‘Secret Conversations’ feature for each and every chat, and both participants need to have the latest version of the app installed for this to work.
Plus, encryption isn’t available for group chats, and you can only access Secret Conversations from the device you started them on. They also don’t support GIFs and videos (images and stickers work fine, though).