This is because the remarketing functionalities of Google Analytics service will work cross-device starting from May 15, 2017.
Here’s the email that Google Analytics sent out:
Dear Google Analytics User,
Remarketing with Google Analytics will soon be enhanced to take advantage of new cross-device functionality available in AdWords and DoubleClick.
If you received this email from Google Analytics, it means that you have Remarketing enabled on your Google Analytics account:
If you log-in to your Google Analytics account you will be notified about this update through an announcement bar:
Here’s how Google explains this update (when you click “See details” link from the announcement bar):
Important update to Remarketing with Google Analytics
Starting May 15, 2017, Remarketing Audiences created in Google Analytics will be enhanced to automatically take advantage of new cross-device remarketing functionality now available in AdWords and DoubleClick. This will allow you to reach your customers across devices when using Google Analytics Audiences.
Our research shows that six in ten internet users start shopping on one device but continue or finish on a different one. With cross-device remarketing in AdWords and DoubleClick, if someone visits your website on one device, you can now reach them with more relevant ads when they search or browse on another device.
Where users have chosen to enable Google to associate their web and app browsing history with their Google account, and to use information from their Google account to personalize ads they see across the web, Google will use data from its signed-in users together with your Google Analytics data to build and define audience lists for cross-device remarketing. In order to support this feature, Google Analytics will collect these users’ Google-authenticated identifiers, which are Google’s personal data, and temporarily join them to your Google Analytics data in order to populate your audiences.
No action is required for these changes to take effect but please review your privacy policies and make any necessary updates to explain what data your business collects and shares with Google.
These changes do not affect your rights to your Google Analytics data, which is still owned by you.
As always, Google users can control their ads experience (or opt out of personalized ads altogether) at My Account.
If you don’t wish to enable Remarketing with Google Analytics, please turn off remarketing data collection.
So what does it mean for your Google Analytics account and/or your websites? Here’s what you need to do:
Answer “Yes” at the “Do you use remarketing services for advertising purposes?” question.
Select “Google AdWords” at the “Select what platforms are you using for remarketing purposes” question.
If you do not plan to use remarketing, follow these steps:
Login to your Google Analytics account
Select a website property
Click “Admin” to reach the Administration section
Google Analytics: Admin link
Click “Tracking Info”
Google Analytics: Tracking Info option
Select “Data Collection”
Google Analytics: Data Collection at Tracking Info
You can disable the “Remarketing” option
Remarketing and Advertising Reporting Features enabled in Google Analytics
You’re required to disclose how you are using remarketing
You’re required to disclose that third-party vendors (like Google) show your ads across other websites
You’re required to disclose that third-party vendors (like Google) use “cookies” to show your ads based on past visits to your website