What is a Device ID?

A Device ID is a string of numbers and letters that identifies every individual smartphone or tablet in the world. The ID number itself is stored on the mobile device and it can be retrieved by any app that is downloaded and installed. Apps typically retrieve the ID to use it for identification when talking to servers.

In the context of mobile advertising, a device ID will be one of two things depending on your operating system. Either is used as the identity which advertisers, marketers and other services will track when looking for a particular type of device:

  • On iOS, a device ID is called the ‘Identity For Advertisers’ (IDFA, or IFA for short).
  • On Android, the device ID is the GPS ADID (or Google Play Services ID for Android). A user is able to access their GPS ADID within the settings menu under ‘Google – Ads,’ as well as reset the ID, and opt-out of ad personalization too.

Why is the Device ID Important?

Device IDs are the easiest way to identify mobile users, as they allow you to track individuals. This not only reveals certain user behaviour (which can be aggregated to identify trends) but it also allows you to put users into cohorts based on understood identifiers such as geographic region, or device. Essentially, if you’re able to track a user’s Device ID, you are able to create a much clearer picture of who they are, and how they behave over time.

If a publisher allows you to track Device IDs from their platform, it’s easy to see whether that user looks at your ad, installs your app and then how they use the app. This is because you can track their ID through the process. Testing users for better understanding of a cohort (such as for creative, or ad optimization) also improves due to usage of unique user IDs.

Reference: “Adjust,” Retrieved – 23 April 2018