Mobile Tutorial Series – What is a Google advertising ID or GAID?

By John Koetsier September 22, 2020

The Google advertising ID is a device identifier for advertisers that allows them to anonymously track user ad activity on Android devices. It has often also been called the Android advertising ID, but Google advertising ID (short form: GAID) is more commonly used.

You can think of the GAID or Android advertising ID as somewhat analogous to a third-party cookie on the web.

Advertisers use third-party cookies to know what actions a user of a particular web browser is taking on their ads on various websites. The Google advertising ID does something similar: it helps advertisers know when an ad has been viewed or clicked in an app, and when an ad causes a conversion.

An app install would be a common tracked conversion using the Google Advertising ID.

The Android advertising ID is a hot topic right now because in iOS 14, Apple has made the IDFA — the iOS version of Google’s advertising identifier — opt-in on a per-app basis, which many web marketers think will reduce the visibility of advertising effectiveness.

The question naturally becomes: will Google make the GAID opt-in as well?

It’s also a hot topic because, in addition to its use in measuring ad campaign effectiveness, the third-party cookie has been used to track people around the web, which has serious privacy implications. Apple has eliminated the third-party cookie from its browser, Safari, and Google will be following suit by 2022. All of which has opened questions about the future of the Google advertising ID on mobile as well.

History of the GAID, or Android advertising ID

Advertisers want to be able to connect ad views with actions.

Before mobile became the dominant means of accessing the internet, cookies served that function in desktop web browsers. Marketers could set a cookie on a website or in an ad and then measure ad effectiveness. However, cookies don’t work well in the mobile world: they work in web browsers, not mobile apps, and we tend to spend most of our time on our phones in apps, not mobile browsers.

In addition, cookies typically have short life-spans … somewhere around one to thirty days.

So the GAID or Android advertising ID took the place of cookies in mobile advertising delivered to Android devices, just as the IDFA did that on iOS devices. Marketers use it to connect app installs or purchases to specific anonymous individuals.

The good thing about GAID from a marketers’ perspective is that in contrast to cookies, Google advertising IDs are semi-permanent device identifiers because they don’t change unless users specifically take an action in their Android device settings. Because few consumers actually do take this action (fewer than 5% in the U.S.), Android advertising IDs can offer a better foundation for a persistent and anonymized consumer profile based at least in part on ad interaction data.

Privacy and GAID (and IDFA)

Privacy has become increasingly important for consumers.

Misuse of advertising identifiers and trackers have created significant problems, and legislation like GDPR and CCPA (the California Consumer Privacy Act) have limited how marketers can collect and use data. The major platforms — especially Apple — have moved to decrease the amount of data that can be collected digitally from consumers.

Interestingly, both the Android advertising ID and the IDFA were actually privacy-focused identifiers.

Each replaced a permanent device ID, the Android ID or ANDI on Android, and the Unique Device Identifier or UDID on iOS. Before Google created the advertising ID, advertisers could track activity on Android phones using that permanent and unchangeable device ID. The Android advertising ID enabled more consumer choice and privacy because people could turn it off or change its value – neither of which is possible with a permanent device ID.

Even so, there is increasing concern that advertising identifiers like GAID and IDFA can also cause significant privacy violations. That has led Apple to make IDFA opt-in and offer SKAdNetwork as a privacy-safe replacement. Google hasn’t said yet what it plans to do with the Android advertising ID, but Google already has potential replacement technologies at least partially in place such as the Google Play Install Referrer.

Using the GAID or Android Advertising ID

When consumers take actions because of ads, like clicking on a banner in an app, playing a video in an app, or installing an app, ad networks can provide the Android advertising ID with information about the consumer action that took place because of the advertising.

This is called attribution, and it attributes actions, or conversions, to stimuli, or ads.

Most media companies do pass Android advertising IDs.

Some media companies, including some large social networks, do not pass device IDs to advertisers but do allow you to target specific IDs within their properties. Singular helps advertisers by associating in-app consumer actions and marketing programs to these semi-permanent identifiers. This helps advertisers understand the effectiveness of their marketing and create powerful customer profiles to understand their audiences.

Using Android advertising IDs and app attribution tools like those offered as part of the Singular Platform, marketers can understand which ads, creative, campaigns, and media partners were responsible for the consumer conversions they want. Using these insights, they can calculate the ROI for all of their ads and tactics, and optimize their campaigns and ads to the most profit-generating tools.

The Android Advertiser ID also enables a marketer to target specific individuals that have taken actions in the past on their mobile devices or find others such as the most highly-engaged users in their apps.

For example:


  • Re-engagement
    • Find people who have installed an Android app and deliver advertising that invites them to relaunch the app
    • Create an audience of lapsed users and advertise to them on their Android phones to get them to come back to the app
  • Offers
    • Identify people who have abandoned items in shopping carts, and present an offer for them to come back and complete their purchases
  • Look-alike audiences
    • Identify devices from users who are deeply engaged and profitable in your app, and ask an ad network or media company to find more people who look like those, and therefore would conceivably be good new users to acquire

This sort of individual targeting has become increasingly common as programmatic media and social media advertising grow in popularity for the marketing of apps. However, they may become harder to achieve, if not impossible, if advertising identifiers like GAID and IDFA get essentially deprecated in favor of more privacy-safe solutions.

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