Unlike traditional text messages, iMessage makes it possible to see when your messages have been delivered to one of your recipient’s devices as well as when they’ve actually read your message.
Although delivery notifications are always enabled, you can choose if you want people sending you iMessages to be able to see the date and time when you’ve actually read their messages.
To access this option, simply go to Settings, Messages and toggle the Send Read Receipts option to whichever setting you prefer.
