Words With Friends has 14.9 million monthly active users and 6.7 million daily users, both on smartphones and on Facebook, according to AppData. The game makes money through ads, an ad-free paid version, and recently through in-game purchase options. And the mainstream popularity of the title helped build buzz for Zynga’s$1 billion IPO.

Some insight to better understand one of the most successful iOs games. This is a nice story on how things need to be done to make millions in the AppStore.