WhatsApp is an instant messaging app predominantly for smartphones. It is a cross-platfom app that is used to send messages, images, videos, audio messages, and user locations. It was founded in 2009 by Brian Acton and Jan Koum. In February 2014 Facebook bought WhatsApp from Acton and Koum for $19 billion. In January 2015 WhatsApp had over 700 million active users making it the most popular instant messaging app and third most popular virtual community in the world behind Facebook and Tencent QQ.
The operating systems the WhatsApp currently works on are: