Some magnet schools have a competitive entrance process, requiring an entrance examination, interview, or audition. Other magnet schools select all students who apply or use a lottery system, or a system combining some elements of competitive entrance and a lottery.
As of February 2016, WhatsApp had 1 billion monthly active users, up from April 2015 when the company announced over 800 million MAU. The company's growth in India is also pretty impressive at around 5 million additional MAU per month (60M in Aug '14).
WhatsApp (Android, iOS, WP8) (Free download, $0.99/year). Remarkably easy setup, automatic syncing with your phone's contacts and a feature-rich, ad-free experience all combine to make WhatsApp (Android, iOS, WP8) a wildly popular mobile messaging app.