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I've seen a lot of people confused by this, so I figured I'd clear it up: "App tracking" here means reading your device ID, called the 'Identity For Advertiser

I've seen a lot of people confused by this, so I figured I'd clear it up: "App tracking" here means reading your device ID, called the 'Identity For Advertisers' (IDFA for short). They do this so that they can cross reference that IDFA with data that other apps have collected on that same IDFA, allowing them to connect the dots that it's the same user. This app tracking transparency feature makes it so that they can't access your IDFA, and can only show you ads based on info you provide within their own app, not from the other apps you use. It keeps your data silo-ed to each app. This is where the whole "I looked up nike shoes on Amazon and now I'm getting nike shoe ads on Facebook" comes from. Without the IDFA, Facebook has no way of knowing what you looked up on Amazon, only what you look up on Facebook.

everdrive 5y ago
>This is where the whole "I looked up nike shoes on Amazon and now I'm getting nike shoe ads on Facebook" comes from. Without the IDFA, Facebook has no way of knowing what you looked up on Amazon, only what you look up on Facebook. Can this really be true? Wouldn't the conclusion be "Facebook can no longer rely on the IDFA for this information, but can probably gather it by a different ID shared between both Amazon and Facebook?"
- disgruntledphd2 5y ago
  This is not true, see my other comment. You are correct, as far as I know (which isn't much, as I'm not really in the industry anymore).
disgruntledphd2 5y ago
> This is where the whole "I looked up nike shoes on Amazon and now I'm getting nike shoe ads on Facebook" comes from. Without the IDFA, Facebook has no way of knowing what you looked up on Amazon, only what you look up on Facebook. That's not really true, as far as I know. FB provide a feature called custom audiences, which can take a set of emails and match them to FB users. Amazon could easily upload this list and use it to target on FB. Apple can't really prevent advertisers/platforms from sharing information from other sources. What they can stop is apps using IDFA as a primary key for a particular Apple user, and that's what they appear to have done.
nonameiguess 5y ago
Facebook and Amazon can both track you individually and correlate accounts because you need an account under your real name to use the service. They can just choose to share this information with each other. This only prevents services from using IDFA to correlate pseudonymous accounts or across services that don't require accounts at all. I especially don't understand the complaint from Facebook with reference to the four plus apps they have where users may very well just use the same account. As it stands, they've been wildly inconsistent about this. Here is Mark Zuckerberg only six weeks ago claiming this change would be good for Facebook: https://arstechnica.com/gadgets/2021/03/as-apple-app-tracking-change-nears-chinese-tech-firms-fight-back/ https://arstechnica.com/gadgets/2021/03/as-apple-app-trackin...

everdrive 5y ago

>This is where the whole "I looked up nike shoes on Amazon and now I'm getting nike shoe ads on Facebook" comes from. Without the IDFA, Facebook has no way of knowing what you looked up on Amazon, only what you look up on Facebook. Can this really be true? Wouldn't the conclusion be "Facebook can no longer rely on the IDFA for this information, but can probably gather it by a different ID shared between both Amazon and Facebook?"

disgruntledphd2 5y ago
This is not true, see my other comment. You are correct, as far as I know (which isn't much, as I'm not really in the industry anymore).

disgruntledphd2 5y ago

> This is where the whole "I looked up nike shoes on Amazon and now I'm getting nike shoe ads on Facebook" comes from. Without the IDFA, Facebook has no way of knowing what you looked up on Amazon, only what you look up on Facebook. That's not really true, as far as I know. FB provide a feature called custom audiences, which can take a set of emails and match them to FB users. Amazon could easily upload this list and use it to target on FB. Apple can't really prevent advertisers/platforms from sharing information from other sources. What they can stop is apps using IDFA as a primary key for a particular Apple user, and that's what they appear to have done.

nonameiguess 5y ago

Facebook and Amazon can both track you individually and correlate accounts because you need an account under your real name to use the service. They can just choose to share this information with each other. This only prevents services from using IDFA to correlate pseudonymous accounts or across services that don't require accounts at all. I especially don't understand the complaint from Facebook with reference to the four plus apps they have where users may very well just use the same account. As it stands, they've been wildly inconsistent about this. Here is Mark Zuckerberg only six weeks ago claiming this change would be good for Facebook: https://arstechnica.com/gadgets/2021/03/as-apple-app-tracking-change-nears-chinese-tech-firms-fight-back/ https://arstechnica.com/gadgets/2021/03/as-apple-app-trackin...