WhatsApp are now going to allow its users to mark messages as 'unread'. Much like with Gmail, you can now add a previously read message back into the inbox, meaning you have no excuse for forgetting to reply to your friends/people who feel like it's acceptable to contact you.
Unfortunately, you still have no bearing over whether the other user sees that you've read the message in the first place, so you're still going to have to reply, or else look like an unsociable so and so.
The update will also allow the user to mute a conversation for eight hours, a week, or a year. To be fair, if you're muting a conversation for a year, it's probably best to just delete the number.
Customised vibrations, message tones, and notifications can now also be created, and there's talk of a return for the Google Drive backup, and a 'low-data' call option for those concerned about their monthly allowance.
These updates will only be available for Android phones, and will need to be manually downloaded, so don't come to us complaining if your stuck with the old system.