Along with the introduction of the iPhone 5, Apple has released the iOS 6 GM (Golden Master) so developers can play around with it free of charge before it goes public on September 19. So, most of the 400 million iOS device users can upgrade.
iOS 6 beta has been available for a couple months now, and we have had the chance to explore some of the great new features of "the world's most advanced mobile operating system"—as Apple calls it.
With iOS 6 GM, Apple has introduced Advertising Identifier, which is aimed at solving the UDID issue. As you may already know, Apple announced that support for UDIDs will be withdrawn in iOS 6, so they can no longer gather information and serve you targeted ads, which they previously did by using your device's unique identifier. In other words, Advertising Identifier is aimed at protecting your personal device information. This new feature will also limit ad tracking in iOS 6.
Here is what Apple says about the new feature of the recently updated iOS 6:
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iOS 6 introduces the Advertising Identifier, a non-permanent, non-personal, device identifier, that advertising networks will use to give you more control over advertisers' ability to use tracking methods. If you choose to limit ad tracking, advertising networks using the Advertising Identifier may no longer gather information to serve you targeted ads. In the future all advertising networks will be required to use the Advertising Identifier. However, until advertising networks transition to using the Advertising Identifier you may still receive targeted ads from other networks.