Founded in 2009 by Brian Acton and Jan Koum, WhatsApp is a cross-platform instant messaging app that allows you to send messages without having to pay for SMS. It can be used to send text messages, video, images, and audio media messages.
WhatsApp handled 10 billion messages per day in August 2012, and by June 2013, reached a new record of 27 billion messages per day. In February 2014, Facebook acquired WhatsApp for $19 billion. By April 2014, WhatsApp had reached half-a-billion active users worldwide.
As of June 2014, the client software for WhatsApp is available for iOS, Android, Windows Phone, BlackBerry OS and selected Nokia and Symbian mobile operating systems.