Apparently, iOS 6 introduced IDFA, "identifier for advertisers", which identifies your device so that advertisers can track you and send you ads. It appears they also introduced IDFV, "identifier for ...
iOS, like most other mobile OSs, has the potential to leak significant chunks of personal information to 3rd-party apps and to ad and tracking networks used by those apps, which in turn also has the ...
For those of you who are not familiar with the topic, a quick search will turn up a lot of hits, e.g. see the researcher's report at Got an iPhone or 3G iPad? Apple is recording your moves - O'Reilly ...