Have you ever accidentally sent a message on WhatsApp that you wish you hadn't? Well, starting today, you can delete it -- as long as you catch it within the first seven minutes. If you do, however, your recipient will instead see a "This message was deleted" alert.
The feature is called "delete for everyone," and is essentially an extension of a previous feature that lets you delete messages, but only for yourself. Hence, it was fairly useless if you had just sent a message to the wrong person, as the recipient could still see it. With today's update, however, when you delete a message, it means that everyone will no longer be able to see it.
That said, this feature only works in the latest update of WhatsApp, and all participants in the conversation must have this latest update for it to work. Seeing as the rollout of this new update is relatively slow, you should probably double check your messages before sending for the time being.