With iOS 6, Apple has officially deprecated the UDID as a valid means for advertisers to track app users. The UDID functioned sort of like a Social Security Number for your iPhone, allowing advertisers and third parties to track your behavior across multiple apps… a troubling privacy concern for many. But UDID tracking also had many beneficial advantages, like allowing developers to troubleshoot crashing apps and the like, which inspired some third-parties when their many companies started releasing their own alternatives to UDID.
Apple wasn’t going to leave advertisers and developers without an alternative to use in their apps, though. New in iOS 6 is two new IDs: IDFA and IDFV. Yes, both IDs still track you, and the IDFA is specifically used by advertisers to collect data on you. But the good news is that this tracking can easily be turned off, and it’s much less invasive than the UDID.