Facebook has begun testing end-to-end encryption for conversations in Messenger. Dubbed "secret conversations," encryption allows you to securely message your friends and loved ones securely, in a way that nobody else, not even Facebook, can see.

From Facebook:

To enable you to do this we are starting to test the ability to create one-to-one secret conversations in Messenger that will be end-to-end encrypted and which can only be read on one device of the person you're communicating with. That means the messages are intended just for you and the other person — not anyone else, including us. Within a secret conversation, you can also choose to set a timer to control the length of time each message you send remains visible within the conversation.

Facebook is using the Signal Protocol built by Open Whisper Systems to develop secret conversations. The company is rolling out the encryption option to only a small subset of people at this time, with a wider rollout is expected later this summer.