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).
1. WhatsApp (First year free, $0.99 per year thereafter). Now that Facebook has decided to pay a whopping $19 billion for WhatsApp, it has to be top on our list-it's the biggest messaging app around by far with a user base that's in love with the service.