Advertiser ID (IDFA/GAID)

Definion of Advertiser ID

Advertiser IDs are unique, resettable device identifiers used by mobile measurement partners (MMPs) to attribute app installs, in-app events, and revenue to their originating ad campaigns. On iOS, this identifier is called the Identifier for Advertisers (IDFA). On Android, it is known as the Google Advertising ID (GAID), or sometimes the Android Advertising ID (AAID).

These identifiers are the technical backbone of deterministic mobile attribution — they allow platforms like Affise MMP to match a user’s ad click or impression to a subsequent install or in-app action with a high degree of certainty.

Types of Advertiser IDs

There are two primary types of advertiser IDs:

Both identifiers work in fundamentally the same way — they provide a way to identify a device for advertising purposes while giving users control over their privacy. The key visual difference is case sensitivity: IDFA uses uppercase letters, while GAID uses lowercase.

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Why Advertiser IDs Matter in Mobile Marketing

Advertiser IDs are the cornerstone of mobile attribution. Without them, mobile marketers would have no reliable way to:

• Track which ads drive app installs — By matching the device’s advertiser ID against click data, MMPs can determine exactly which campaign led to an install.

• Measure campaign performance — Advertiser IDs allow marketers to see which channels, creatives, and partners deliver the highest-value users.

• Optimize ad spend — Understanding which campaigns drive conversions enables real-time budget shifting to maximize Return on Ad Spend (ROAS).

• Detect ad fraud — If an install arrives without a corresponding valid click tied to an advertiser ID, it can be flagged as fraudulent.

• Track in-app events — Beyond the install, advertiser IDs enable attribution of purchases, subscriptions, level-ups, and other in-app events back to the original ad source.

In short, advertiser IDs are what make mobile attribution possible — they are the technical link between a user’s ad exposure and their subsequent actions inside an app.

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How Advertiser IDs Work with Affise MMP

Affise MMP (Mobile Measurement Partner) uses advertiser IDs as a core component of its attribution engine. Here’s how the process works step by step:

1. The User Clicks an Ad

A user clicks on a mobile ad. This click passes through a unique tracking URL generated by Affise MMP, which logs the source, campaign ID, and timestamp.

2. The User Installs the App

The user is redirected to the Apple App Store or Google Play Store and downloads the app.

3. The SDK Initializes

When the user opens the app for the first time, the Affise MMP SDK (which the developer previously integrated) is initialized. The SDK captures:

• The device’s advertiser ID (IDFA on iOS or GAID on Android)

• The install event

• Timestamp, IP address, and user agent

4. Attribution Matching

Affise MMP compares the incoming install data against the click data stored from Step 1. The key matching criteria include:

• Device identifiers (IDFA/GAID matching — deterministic attribution)

• IP address, user agent, and OS version (probabilistic fingerprinting when the ID is unavailable)

• Timestamp windows (e.g., last click within a 7-day window)

5. Conversion Recorded

If the click and install match within the predefined time window, a conversion is recorded.

6. Postback Sent

Affise MMP sends a postback notification to the ad network, confirming the install was successful.

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Privacy Changes: The End of the IDFA Era

The mobile advertising landscape has undergone a dramatic shift in recent years, driven by privacy regulations and platform policy changes.

iOS 14.5 and App Tracking Transparency (ATT)

With the release of iOS 14.5 in April 2021, Apple introduced App Tracking Transparency (ATT) — a framework requiring apps to obtain explicit user consent before accessing the IDFA. Key implications:

• Users are opted-out by default

• Apps must present a tracking prompt and users must select “Allow Tracking” to grant access

• Users can configure opt-ins and opt-outs per app in Settings

• Users can toggle off “Allow Apps to Request to Track” entirely, preventing the prompt from appearing

As a result, IDFA availability has dropped significantly — industry reports suggest opt-in rates vary by region and vertical, generally ranging from 30% to 50% .

Android Privacy Changes

Google has followed suit with its own privacy initiatives:

• From Android 12, the GAID is zeroed out for users who opt-out of ad personalization

• From Android 14, users can customize ad settings or completely remove the GAID

• Privacy Sandbox on Android, expected for full rollout in 2025, will further reduce reliance on the GAID

The Impact on Mobile Attribution

These changes have made deterministic tracking (relying solely on IDFA/GAID) increasingly unreliable. To address this, Affise MMP supports several alternative approaches:

• SKAdNetwork (SKAN) — Apple’s privacy-preserving framework that provides aggregated, delayed attribution reports rather than user-level data

• AdAttributionKit (AAK) — Apple’s newer attribution framework introduced at WWDC 2024

• Probabilistic modeling and fingerprinting — Analyzing IP addresses, device type, and OS version to match users when deterministic identifiers are unavailable

• Privacy Sandbox — Google’s evolving privacy-preserving alternative to traditional device tracking

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How Affise MMP Handles the New Privacy Landscape

Affise MMP has proactively adapted to these privacy changes, ensuring marketers can continue to measure campaign performance even as advertiser ID availability declines:

Affise MMP acts as a neutral, unbiased layer between advertisers and ad networks, ensuring accurate tracking regardless of the underlying identifier availability.

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Best Practices for Advertiser ID Tracking with Affise MMP

To maximize tracking accuracy and campaign performance in the current privacy-first environment, follow these best practices:

1. Implement Proper Consent Management

For iOS apps, integrate the App Tracking Transparency framework and present a clear value proposition for why users should enable tracking.

2. Configure Fallback Measurement Methods

Set up SKAdNetwork for iOS attribution and prepare for Privacy Sandbox integration on Android. Ensure Affise MMP can handle both deterministic device ID matching and probabilistic modeling.

3. Test Across Permission Scenarios

Verify that your implementation works properly for both opted-in and opted-out users.

4. Use Affise MMP’s Full Toolkit

Leverage Affise MMP’s comprehensive attribution capabilities, including:

• Deterministic attribution when IDFA/GAID is available

• Probabilistic attribution when identifiers are unavailable

• Postback integration with ad networks for real-time campaign optimization

5. Monitor Opt-in Rates

Track your IDFA/GAID opt-in rates across regions and verticals to understand the impact on your attribution coverage and adjust your measurement strategy accordingly.