What Limited Ad Tracking Was
Limited Ad Tracking was Apple's original control over advertising tracking on iOS. In the Privacy settings, users could turn on "Limit Ad Tracking" to tell apps and ad networks not to use their advertising identifier for interest-based ads, retargeting or measurement.
At first, LAT was an honour system. Apps could still read the IDFA and were expected to respect a flag. From iOS 10 in 2016, Apple enforced it: when LAT was on, the IDFA returned all zeros, so there was nothing to track with.
LAT was an opt-out. Tracking was on by default, and only users who knew about the setting turned it off. Most iOS users never changed it, so most devices still shared their IDFA before 2021.
What Replaced It: App Tracking Transparency
Apple announced App Tracking Transparency with iOS 14 and enforced it from iOS 14.5 in April 2021. ATT flipped the default. Every app that wants to track users across other companies' apps and websites, or access the IDFA, must now show a system prompt and get permission. Without permission, the IDFA is zeroed.
The global LAT toggle was replaced by an "Allow Apps to Request to Track" setting. When that is off, apps cannot even show the prompt, and every app is treated as denied. Each app's permission can also be changed later in Settings.
Because ATT is opt-in, IDFA availability on iOS fell sharply. Attribution on iOS moved toward Apple's privacy frameworks, SKAdNetwork and later AdAttributionKit, and toward signals that do not depend on the IDFA.
The Android Side
Android followed a similar path more slowly. Google Play services offered an "Opt out of Ads Personalization" setting that set a limit ad tracking flag alongside the Google Advertising ID (GAID). Apps were expected to respect it.
From Android 12, users can delete their advertising ID. Apps then receive a string of zeros instead of an ID. Apps targeting Android 13 and later must declare the com.google.android.gms.permission.AD_ID permission in their manifest to read the advertising ID at all. Google Play policy also restricts linking the advertising ID to persistent device identifiers or personal data without consent.
How Attribution Works Without the Advertising ID
When the advertising ID is zeroed or missing, MMPs use other signals. On Android, the Google Play Install Referrer gives a deterministic link between a store visit and an install. Ad click IDs such as gclid and fbclid connect installs to clicks when they survive the redirect. On iOS, Apple AdServices attributes Apple Ads installs, and SKAdNetwork and AdAttributionKit postbacks report campaign-level results with privacy thresholds. Probabilistic matching on IP and user agent covers the remaining gaps.
Linkrunner matches installs deterministically first, using the Google Play Install Referrer, ad click IDs, device IDs where the user allows it and Apple AdServices for Apple Ads, and falls back to IP and user-agent matching only when no deterministic signal exists. The IDFA is collected only with ATT consent. See SKAN and AdAttributionKit for iOS privacy measurement in Linkrunner.
Why the Term Still Comes Up
You will still see "LAT" in older MMP reports, raw data exports and postback macros, often as a field showing whether a device had tracking limited. On current iOS that field effectively reflects ATT status. When you read historical data from before 2021, remember that LAT users were a minority, which is why iOS cohorts before and after ATT are not directly comparable.
Planning Measurement Without Advertising IDs
Whatever the setting is called on each platform, the direction is the same: fewer users share an advertising ID, and measurement has to work without it. Plan for that rather than hoping opt-in rates rise.
Start by knowing your coverage. Track the share of installs where an advertising ID is available, by platform and OS version, and the share attributed through each method: install referrer, click IDs, Apple AdServices, SKAdNetwork or AdAttributionKit, and probabilistic fallback. This shows how dependent your reports are on each signal.
Then strengthen the signals you control. Keep click IDs intact through redirects, use first-party sign-in so conversions can carry your own user ID and, where consented, hashed email or phone, and set up conversion value mapping for SKAdNetwork and AdAttributionKit so iOS campaign data is useful. Teams that do this see far less disruption when platform rules change again.