When Google had purchased the Double Click advertising network in 2007, the company’s founder Sergey Brin said that privacy would be the company’s “number one priority when we contemplate new kinds of advertising products.”

In June 2016, Google changed the way it keeps a track of its users across the internet and users’ personally distinguishable information from Gmail, YouTube and other accounts has been combined with their browsing records from across the web.

An analysis of the changes conducted by Propublica details how the company quietly updated its privacy settings in June to delete a clause that said “we will not combine DoubleClick cookie information with personally identifiable information unless we have your opt-in consent.” The company has previously pledged to keep these two data sets separate to protect individuals’ privacy.

By default, the change is enabled for new Google accounts. Existing users were prompted to opt-in to the change this summer through a request with titles such as “Some new features for your Google account.”

Instead, Google has substituted those privacy protection deeds with some new language that says that the tech giant “may combine personal information from one service with information, including personal information, from other Google services.”

According to the ProPublica report, “The practical result of the change is that the DoubleClick ads that follow people around on the Web may now be customised to them based on your name and other information Google knows about you.

“It also means that Google could now, if it wished to, build a complete portrait of a user by name, based on everything they write in email, every website they visit and the searches they conduct.”

Google spokeswoman Andrea Faville has sent out a statement explaining the need for the change. She claims, “Our advertising system was designed before the smartphone revolution. It offered user controls and determined ads’ relevance, but only on a per-device basis. This past June we updated our ads system, and the associated user controls, to match the way people use Google today: across many different devices.

“Before we launched this update, we tested it around the world with the goal of understanding how to provide users with clear choice and transparency. As a result, it is 100% optional–if users do not opt-in to these changes, their Google experience will remain unchanged.”

If you do not wish to be tracked, you can visit the ‘Activity controls’ on Google’s ‘My Account’ page, and uncheck the box marked “Include Chrome browsing history and activity from websites and apps that use Google services”. You can also delete past activity from your account.