Identity for advertisers (IDFA)

An IDFA is a unique, random identifier that Apple assigns to every device.

What is the Identity for Advertisers (IDFA)?

Kind of like a cookie for devices, the IDFA was traditionally used by advertisers to measure how users interacted with their ads and along the user journey.

However, unlike browser cookies which have a short(ish) lifespan, an IDFA sticks around until a user manually resets it. 

As part of Apple’s move to make iPhones more privacy-centric, they put the choice of measurement in users’ hands and users now have to opt-in to measurement. This choice comes in the form of a prompt called the App Tracking Transparency Framework, or ATT.

This opt in prompt is the newest iteration (previously there was LAT) in Apple’s innovations around privacy.


Why was IDFA so important to mobile measurement?

By assigning an ID to a given iOS device, advertisers were able to obtain more granular information about users’ activities within a given campaign helping advertisers optimize both strategies and budgets.

That said, as we mentioned above, Apple moved to an App Tracking Transparency framework where users need to opt-in for advertisers to measure their activity. This means that measurement just got a bit harder.

Is the IDFA still relevant for measurement?

The IDFA certainly isn’t dead and the latest statistics put ATT opt-in rates at around 39%.

While Apple offers a solution called SKAdNetwork – a way for advertisers to attribute impressions and clicks to app installs on iOS apps without revealing any user-level or device-level data – it’s not perfect. Some have cited that as a metaphorical walled garden there could be issues with ad networks “grading their own homework” as they are the ones reporting what’s happening on their own networks in contrast to an unbiased third party.

As the ecosystem evolves, the IDFA will indeed become less relevant in the discussion around measurement and give way to tools that involve machine learning and predictive analytics.

Get the latest marketing news and expert insights delivered to your inbox