Google announced a change to the ad delivery system on its email service, Gmail.
Today, if you open a message that, for example, has confirmation of a hotel stay in Chicago, Gmail can show you flight announcements for Chicago.
But there are not always ads relevant to the content of the message. Imagine that you received an email congratulating you on your birthday. If there are no birthdays-related announcements, Gmail can show you flight announcements to Chicago. In this case, ads related to the last email you opened.
According to Google, the process for displaying ads is fully automated: no person is involved in the selection of ads, and no email or personal information is shared with advertisers.
The company released the video (in English), which can be watched below, in which it explains the changes in the ad system: