This section covers all information about the cross device feature in Custom and Lookalike Audiences.
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Description
Using our proprietary cross-device technology we are able to link multiple devices to one user. This means we are able to link tablet X, laptop Y and smartphone Z to the same user. You can leverage cross-device in the DMP by checking the checkbox when building a Custom Audience or Lookalike Audience. Enabling cross-device for your audience will result in more devices of the same user added to your audience. This will likely increase the reach of your advertising campaign targeting this audience (audience extension). The Cross-Device Report gives you more insight into cross-device for your account. You are able to see the amount of cookies you collected vs. the real users (matched through cross-device).
Model
The images below describe how the cross-device model works. The cross-device model is based on deterministic data like hashed email addresses and hashed phone numbers. All data of a user is linked to a Master ID which contains information about the user. The data is mainly collected through the on-site pixel. In order to collect data like hashed email addresses please enable the User Data modules in Data Collection (for more information see: On-Site Pixel Modules).
- User did not enter any detail on any of his devices. The DMP identifies three separate users.
- User logs in on the website using his email address on his desktop and smartphone. The DMP is now able to link desktop X and smartphone Y to the same user.
- User enters email address somewhere on the website. The DMP is now able to link all three devices to the same user.
Privacy & Compliance
All data attributes used for our cross-device model is stored in an hashed format. It is not possible to turn hashed data back into its original string. For example, we store hashed email addresses in the following way:
- We collect an email address (e.g. johndoe@mapp.com).
- The hash algorithm is applied to the email address (e.g. johndoe@mapp.com is converted to b7f15e29036c25671f7ef00eb2595343).
- The email address is now converted to a unique hashed value and stored in the DMP.
The DMP uses several hash algorithms like SHA1 and SHA256. We use opt-out cookies for users who opt-out. If a user opts out on a device, we will no longer track that user on that specific device.