Apple has published new guidelines for developers submitting apps to the iTunes store that serve ads. The Cupertino, Calif. company said it will reject any mobile app that does not use Advertising Identifiers. The IDFA is a unique ID for each iOS device and is the only way to offer targeted ads across its network. Similarly, if the developer indicates that the app uses the IDFA, but does not have built-in ad functionality or does not display ads properly, Apple could reject the app. If the developer indicates that the app does not use the IDFA, but it does, Apple will put the app in the Invalid Binary status. For many reasons, it has become increasingly important to identify content-related ads in apps, as more developers use deep links to help people find relevant content. Mobile deep links contain a uniform resource identifier with all the information needed to directly find a particular location within an app from another application or search engine. Bing uses Bing App Link, whereas Google offers App Indexing. Mobile advertising continues to become increasingly important to Apple. In late August, Apple formally released a new ad format in iAd, and in June published an overview on how to monetize apps in the iAd network. The overview also highlights new ad formats for iPhone, iPod touch, and iPad apps running on Apple's network. Apple has expanded its iAd advertising network into 16 countries or regions, expanding into Russia and Switzerland through the iAd Workbench. Apple touts the platform as a simple way to advertise in apps to the millions of people who use Apple products. The platform lets app developers choose your audience, set the price to pay for ad targeting, and create a campaign. Apple is preparing to make an announcement on Sept. 9.