IDFA sounds like alphabet soup, but it is just a privacy-compliant way to track users without collecting personal data. Here is the plain-English breakdown.

Let us break it down for you. IDFA is just a new phrase used for tracking online user activity, only this time without collecting any Personal Identifiable Information, or PII, which is what got the digital advertising industry in trouble.
IDFA is Apple's iOS Identifier for Advertisers. Google has one too, GPS ADID, which stands for Google Play Services ID for Android. Apple is able to track users and resell that data to advertisers while maintaining compliance with GDPR and CCPA by assigning a random identifier to a user's device and completely ignoring any PII. With cookies crumbling all around us, we need IDFAs and GPS ADIDs in order to track prospects and deliver customized advertising experiences.
Just like with cookie tracking, users can opt out of IDFA by going into their settings under Ad Preferences. Apps accessed via the Apple App Store must deliver a clear message upon download that makes it easy to opt out. Bad for business, good for user privacy and legal compliance. Apps with logins are not impacted since users consent at registration. To date, it is estimated that about 20 percent of iOS users have opted out.
One way we work with clients to prepare for a cookieless future is by ensuring proper collection and retention of first-party data. Our team can help you identify the missing pieces of your MarTech stack. As for attracting new customers, we'll need to go back to basics. Brand-building tactics such as contextual targeting, TV, radio, and out-of-home are going to experience a much-deserved comeback.