What Is Identifier for Advertisers (IDFA) on iOS?

By Vungle | August 12, 2021

For years, Apple’s Identifier for Advertisers was the cornerstone of user-level behavioral tracking for advertisers. The release of iOS 14.5 changed all that.

Mobile ad businesses are constantly trying to serve the right ad to the right user at the right time, and on iOS, the IDFA or “identifier for advertisers” plays a big role in making that happen.

IDFA helps ad networks and demand-side platforms (DSP) pair the right audiences with the right ads, which ensures that they’re able to deliver value to advertisers in the form of enthusiastic and engaged users. The users get value from discovering new mobile apps and mobile games, brands, and products that fit their needs. Making all that happen at scale is easier said than done, however, and requires an automated solution for pairing users with ads they’ll engage with. That’s where IDFA comes in.

What Is identifier for advertisers (IDFA)?

Apple’s IDFA is a string of characters unique to every iOS device that is made available to app publishers, and subsequently advertisers, for the purposes of measuring and evaluating user behavior in the interest of delivering better advertising experiences. Unlike Apple’s UDID or “unique device identifier,” users are free to reset their device’s IDFA. Doing so erases the original value and replaces it with a new one.

This puts advertisers and publishers in the position of having to treat any newly observed behavior as belonging to a new device profile, as there is no way to tie the new IDFA to the old one, even though it may be the same person using the device. The same can’t be done for UDID, which is a persistent value associated with the device that can be accessed by developers using an integrated development environment (IDE) like Xcode but can’t be made available to advertisers and publishers for the purposes of ad targeting.

What is IDFA used for in mobile advertising?

Mobile ad businesses are always trying to pair users with advertisements for products, apps and games, and content that they think users will find most interesting. Doing so is a matter of pairing a user’s interests with an overlapping mobile ad campaign, but the first step is actually knowing what the user is interested in.

IDFA affords mobile ad businesses the informational infrastructure necessary to build a unique user profile that can be used to make decisions about which advertisements to show to a user and when. For example, if a mobile ad network stores and tracks an IDFA for someone who spends a lot of time playing different mobile golf games, they’re able to keep track of that information in their own customer data platform.

This profile can then be checked and compared against the stock of ad campaigns that an ad network has to serve whenever it comes time to show that user an ad. If that same user then decides to watch a rewarded video ad or comes across a medium rectangle ad (MREC) in a mobile content feed, the ad network serving that ad has the information necessary to know that it would be better to serve an ad for another golf game than, say, a first-person shooter.

By delivering better advertising experiences to their audiences, ad networks and other mobile advertising businesses can help their customers acquire the right users for their offering. This also prevents the users themselves from being bombarded with ads for products or services that don’t interest them.

Why did Apple make IDFA opt-in on iOS?

The years leading up to the release of iOS 14 were characterized by growing global concern for user privacy. Data breaches from major companies led to private user information being made more-or-less publicly available, allowing bad actors to exploit that information for personal gain. This, plus a growing public sentiment that behavioral data constitutes private property, led to Apple’s decision to change how advertisers and app publishers were allowed to gather information.

When Apple announced the release of iOS 14, it included a key change in how publishers and advertisers would be allowed to collect and store a device’s IDFA. Instead of being granted discretionary access to a device’s IDFA via an ad network’s SDK integration, apps would now need to present users with a pop-up dialogue — Apple calls it the App Tracking Transparency prompt — that explicitly asks them if they agree to allow the app itself to track their behavior across the web and other apps.

Related Article: What Is App Tracking Transparency (ATT) and How Does It Affect Mobile Marketing?

Agreeing to be tracked reveals the device’s IDFA to the app, allowing it to be transmitted to ad networks for use in ad targeting. Not agreeing, however, prevents the app from accessing it. Ad networks can still register that a session has been started within the app, but no unique information is passed that would allow them to know who it is that is using the app, or what ads they would be most interested in.

How Vungle delivers value for advertisers even without IDFA

Whether you agree with Apple’s decision or not, there’s no going back to a world where IDFA was as openly accessible as it once was. Even though some users will agree to be tracked, advertisers need to plan for contextual advertising practices to become the new standard when operating in the iOS ecosystem, and Vungle is ready. Our 2021 acquisition of leading contextual ad intelligence platform GameRefinery by Vungle allows us to target ad campaigns using thousands of unique variables and tags not available to other ad networks. Better still, AlgoLift by Vungle gives advertisers the predictive intelligence necessary to hit their ROAS goals with over 95% accurate LTV predictions.

Get in touch with us to learn more.