Advertisers display ads within these apps, and Facebook shares the ad fees with the
app developers. App-install ads, and ads within apps, are the largest single source of
Facebook mobile ads. There are an estimated 8,000 app developer firms in the United
States alone, and they have created over 25,000 Facebook platform apps. Facebook users
install about 20 million apps every day. These apps range from games like FarmVille,
Words With Friends, and Mafia Wars, to music apps like Spotify and Pandora, to charity-
oriented apps like Social Vibe and Charity Trivia. App ads, and in-app ads, have become
central to Facebook’s mobile strategy. In-app ads have an advantage over standard News
Feed ads: they are not perceived to be as disruptive or annoying as News Feed ads, and
users are more willing to experience the inconvenience of being exposed to ads in return
for a free game.