Facebook announced that it’s now allowing developers and marketers to push targeted ads based on users’ app preferences and purchases with a new targeting system. Speaking at Mobile DevCon 2013 in London, Facebook developers showcased a new targeting field in the latest SDK for a feature called Custom Audiences, which will result in more relevant, targeted ads being displayed on both websites and native apps that pull from individual user preferences and purchase data. This means that a retail app could reach out to Facebook users with additional products that they might be interested in based on purchase history tied to a name. The Custom Audiences feature works by helping marketers find new customers among Facebook’s existing users via email addresses, phone numbers, Facebook user IDs or app user IDs to make a match. Thus developers can use information about offline audiences to target the online population.