Mobile Data Primer: The Mobile Ad ID

The Mobile Advertising ID, also known as a Mobile Ad ID or MAID, is the key to efficiently and anonymously identifying, understanding and targeting mobile app users.

Publishers and marketers alike rely on accurate data provided across mobile devices to grow their business and serve their audiences better.

MAID Advantages

The Mobile Ad ID is a generic term for strings of hexadecimal digits assigned to a mobile device by Android or Apple.

Basically, Mobile Ad IDs are the cookies of the mobile world. On a desktop browser, cookies provide a snippet of code to anonymously and semi-persistently identify a user to ad networks and sites. In mobile applications, the Mobile Ad ID does this job but with a critical distinction:

  • Cookies are set by websites, publishers or ad networks, each maintaining their own cookie. This requires a costly and inefficient practice of “cookie syncing” to move data from one company to another.
  • MAIDs are set by the OS and are common across all app publishers; there is no need to sync data from one app to another.

One drawback to this framework is that the OS has tremendous control over the ad environment, which poses a systemic industry risk. But the benefits of a persistent ID system are obvious. Everything in mobile is connected to the Mobile Ad ID; it serves as the linchpin of mobile advertising and analytics.

How the MAID is Used

For app publishers, the MAID makes it possible to collect all sorts of data about their users using a stable anonymous identifier — from demographics to behavioral. This data helps record app user history as well as inform product iterations and other improvements.

For marketers, the MAID makes strategic targeting possible. They can reach a specific audience within an app, or retarget their own audience across other similar apps.

Here’s how it works:

When you open up an app on your mobile device that serves ads, your MAID goes out on the ad network and a complex system of automated bidding services compete, instantaneously, to fill that ad as the screen loads. The ad that is served to you is based on what advertisers know about you and what they are willing to pay. The more that advertisers know about a MAID in advance, the more than can accurately price what they are willing to pay for an ad to that MAID.

Now let’s say you click on the ad. On your way to the destination, a tracking system grabs your MAID and notes the response. Any further action you take — like downloading the associated app or subscribing — is also attached to your MAID. Now the marketer or publisher is able to see what types of people saw the ad and how they responded, and is thus able to further refine their targeting or deliver a more tailored experience to their audience.

Consumer Privacy, Then & Now

A critical feature of the modern Mobile Ad ID is it allows users to stay anonymous while still being identifiable on ad networks, exchanges and analytics platforms:

  • Companies are prohibited from making permanent connections between users and MAIDs
  • Users can reset their MAIDs
  • If a MAID is deleted, the data must be deleted

A precursor to the MAID was the hardcoded machine ID, known as the Unique Device Identifier or UDID, which linked the consumer and device to online behavioral data. These standards were known as Android ID and Apple UDID and were the early IDs that advertisers started to use to help power their advertising.

Consumers were unable to reset these IDs, which led to privacy problems and other concerns. Apple took a stab at deprecating the UDID, in turn generating other problems like the inability to measure an ad’s effectiveness. Other industry players tried to create a new open standard “Open UDID” but it quickly died when Apple introduced their advertiser-friendly standard. Google followed suit a few months later with their own standard.

Today, current MAID standards are as follows:

  • Apple’s Mobile Ad ID is known as the IDFA, or ID for Advertisers. Generally the industry has agreed to uppercase IDFAs, though technically it shouldn’t be case sensitive. An example: 231A005B-700F-4119-zB1CE-991EAB2B605D.
  • Google’s Mobile Ad ID is known as AAID, or Android Advertising ID. This is different than the Android ID, which was Android’s permanent device ID. Generally, the industry has agreed to lowercase AAIDs, although it also technically should not be case sensitive. An example: c14e7fb1–4476–4b21-ba18–063-c35c0a3b

Unlike UDIDs, these numbers are not hardcoded to a mobile device and can be reset or blocked by users. Both Apple and Android users can reset their MAIDs to flush all data. Apple users can also block ad tracking entirely, which resets the MAID to all zeros. Both companies spell out in the terms of service they have developers sign that if a user resets their MAID, there should be no attempt to link the old and new MAIDs.

There are multiple self-regulatory agencies that cover the online and mobile advertising worlds; their guidelines generally state that MAIDs should not be connected to individuals without consumer consent. They often also offer opt-out options through their websites; however, an app must be a member of the regulatory group for the opt-out to be effective, so in our opinion users concerned about privacy are better off limiting ad tracking directly on their devices.

MAID in the Future

As more and more ad spend moves to mobile, it’s important for both marketers and mobile users to understand how mobile information is collected, stored, and used. The amount and types of data that marketers can learn about mobile users is only increasing, so it is incumbent upon app publishers, analytics firms, and data companies to make sure that they respect users’ choices about how data connected to the Mobile Ad ID is handled. That will result in a better, healthier mobile ecosystem for everyone involved.