Precise instructions to find the advertising ID for your mobile device vary by device platform (iOS or Android).

How to find IDFA on iPhone
For iOS Devices, including iPhone, iPad, and iPod touch, at present, the advertising ID on iOS devices is hidden from users by Apple by default but can be retrieved with third-party apps. Apple calls this identifier an “Identifier for Advertisers” or IDFA. An Apple IDFA is somewhat analogous to an advertising cookie, and enables advertisers to understand that a user of a particular phone has taken an action like a click or an app install.

In order to find your Apple IDFA, a third party tool is required. There is a wide selection of apps with the capability on the App Store. Below are a selection of apps for iOS that can show a device’s IDFA to users.

For Android
Although the Android ID was used historically for mobile ad tracking, as of August 1st, 2014 Google has required all new app releases to utilize the Android Advertising Identifier. Android’s Advertising Identifier, which was first introduced in October 2013, is analogous to the IDFA on iOS.

To find your Android Advertising Identifier, open the Google Settings app on your Android device and click on “Ads.” Your Advertising Identifier will be listed at the bottom of the screen.

Resetting your Device ID
Please consider that resetting an IDFA or Android Advertising Identifier may invalidate systems designed to respect your choices in advertising. Resetting either identifier may require you to submit any requests or forms again.

If you advertising ID is shown as a string of only zeroes, your device is already set to limit ad tracking by default.