Apple’s IFA is short for Identifier For Advertisers. Apple’s IFA is a random, non-permanent, and anonymous unique number tied to an Ipad or Iphone and that is used by app editors and networks for marketing and advertising purposes. It can be considered as the cookie for Apple’s mobile devices.
As for a cookie, an IFA doesn’t identify a user personally and users can delete it or opt-out from their smartphone parameters.
IFA made its appearance with iOS6 deployment and replaced the banned UDID.
Apple’s IFA tracks only users when using mobile applications and not when browsing.