Mozilla’s controversial in-browser advertising scheme is going mainstream. After announcing its intentions in February and testing the receptivity of ads this past year, the Mozilla Foundation is bringing ads to the masses on both desktop and mobile.

The ads are showing up as thumbnails, or Tiles, whenever you open a new tab. These thumbnails have traditionally been reserved for frequently visited sites as quick shortcuts. That functionality will remain but now, paid advertisements are being thrown into the mix.

In a blog post on the matter, Mozilla VP of Content Services, Darren Herman, said the first advertising partners are CVS Health and their media agency Mindshare North America as well as online accommodation booking site booking.com.

It’s worth pointing out that while Mozilla does collect information as it relates to ad performance (think page impressions, clicks and ad placement), it’s done in “aggregate form” which means none of it is personally identifiable.

The good news here is that users can opt out of the advertising program if they so choose. To do so, simply open a new tab page, click the gear icon at the top right of the browser window and select either Classic or Blank (Enhanced is the version with ads).

As you can likely surmise, Blank mode will simply show a blank new tab while Classic will show site history thumbnails only.