When you receive an iMessage on your iPhone, the sender can know the status of your message using read receipts. By default, this feature is enabled on your iPhone and when you read the sender’s message, they will know that you’ve read it, similar to WhatsApp’s blue check marks.

If this feature doesn't match your privacy preferences, you can disable read receipts on your iPhone.

Please note: This feature only supports iMessage, so don't worry if you're receiving regular text messages. This feature doesn't work for regular text messages or group messages.

Read Receipts is a feature that notifies the sender when the recipient reads their messages. This feature is especially useful for time-sensitive or important messages.