WhatsApp on Monday made the announcement that it would be introducing a new feature called "Chat Lock." This feature is intended to provide users with an additional layer of security for their most private conversations. 

The app will also hide the contents of that chat from notifications when you lock it. You can lock a chat by selecting the lock option by tapping the name of a one-on-one or group chat. To uncover these visits, you need to gradually pull down on your inbox and enter your telephone secret phrase or biometric.

Turn on chat lock
You can turn chat lock off or on within the chat’s info for each chat you want to lock. If you don’t have your device authentication set up yet, such as your phone passcode, fingerprint or Face ID, you’ll be prompted to set it up before locking a chat.
How to turn on chat lock:
1 Tap chat info > Chat lock.
2 Tap Lock this chat with fingerprint or Lock This Chat with Face ID.
3 Tap View to see the chat in the Locked chats folder.

View your locked chats
You can view your locked chats in the Locked chats folder.
How to view your locked chats:
1. Go to the Chats tab and swipe down.
2. Tap the Locked chats folder.
3.Confirm your Face ID or touch the fingerprint sensor to unlock.
4. Tap the chat to view or send a message.
Turn off chat lock
You can turn off chat lock in the chat’s info.
How to turn off chat lock:
1. Tap chat info > Chat lock.
2. Toggle off and confirm your fingerprint or Face ID.