Previously, double check marks just indicated that the messages had been received.
The Frequently Asked Question section in WhatsApp’s website reveals that a single check mark next to messages by the sender indicates that the message has been successfully sent.
The regular double check mark that all WhatsApp users are familiar with still indicates that the message has been successfully delivered to the recipient while the newly-added feature — blue-coloured double check mark— means recipients have read the messages.
Users can also retrieve information on the exact time that their messages were read by recipients by checking the info section after selecting the message that was sent
