Developers love them, advertisers love them, and companies are raking in cash—all thanks to the little buttons in mobile advertisements that urge you to download an app. See also: How Post-IPO Twitter Could Make Billions Without Alienating Users Twitter is the latest company to introduce these new mobile advertisements. Today the company announced that developers and advertisers can urge mobile Twitter users to download applications through these so-called app install ads, and reach up to one billion mobile devices through the MoPub Marketplace, the advertising startup the company acquired last year.