If you’ve got a generic announcement to make - an invite to a weekend BBQ or an intervention about your friend's unhealthy obsession with KFC - and you don’t want to do it on the loudmouth platform that is Facebook, this feature works in pretty much the same way as BCC-ing people in an email.
Your recipients will get the message as if it was a privately composed one, oblivious to the fact that you’ve sent the exact same invite to 342 other people. Sincerity? What's that?
How: On the top left hand corner of your WhatsApp Chats window, just below the search bar, you’ll notice a Broadcast Lists. Tap on it for the option to create a new list of contacts you want your message to go out to, and message away like you would normally.
Read more at http://www.stuff.tv/features/11-secret-whatsapp-tricks-you-probably-didnt-know-about#M2EPRxBkCiX3VG8k.99