What Does Identifier for Advertisers (IFA) Mean?
Identifier for Advertisers (IFA or IDFA) is a temporary device identifier used by the Apple set of handheld devices. It provides device identification while giving end users the ability to limit the device/consumer information accessed by advertisers or apps. A successor of Unique Device Identifier (UDID), IFA is available on all devices with versions iOS 6 and later.
Techopedia Explains Identifier for Advertisers (IFA)
IDFA replaces and circumvents UDID's security and privacy issues. IDFA is a like a typical, yet random, serial number that is assigned to each iOS-powered device. Unlike UDID, IDFA is non-permanent and may be activated or deactivated by the user. Based on the user’s activity, the IDFA is sent to the advertising server, which, in turn, displays relevant ads. However, unlike UDID, IDFA does not identify the device or user. Rather, it groups different users by similar search or browsing activity for relevant and targeted advertising.