Facebook has started rolling out a new update for Facebook Messenger which brings in the earlier hinted, ‘Secret Conversations’ feature. The feature basically lets you chat with your friend via end-to-end encrypted conversation. 
A similar feature is currently available in WhatsApp but unlike in WhatsApp, one has to manually enable the feature and it does not work across platforms. After updating, one has to open the messenger app, tap on the friend (username) with which he wants to have the Secret conversation and activate the feature. Additionally, there is also a timer option next to the Secret Conversation feature which lets you set a duration after which the message will be erased.
As of now, it limits the conversation to one device only. In other words, if you log in with any other device, it won’t show up the secret conversation which was started in the previous device. Furthermore, the feature doesn’t support GIFs and videos exchange in the initial phase but hopefully it will in future. The conversations under this feature is saved separately from regular messenger conversations.
Currently, the update is gradually rolling out to some beta users for testing, hence not available in Google Play Store or Apple App Store. Meanwhile, if you are a beta user and can’t wait for the update, we would advise you to wait a little bit more as the update can come anytime.