Mozilla will start showing advertisements for "hand-picked" partner websites and locally popular sites to new users of its Firefox browser, the company announced Tuesday. The ads will populate in the "Directory Tiles" shown when users open a new tab.

Normally, on a fresh install of Firefox, users who open a new tab see eight blank boxes surrounding one that provides a quick link to a "Welcome to Firefox" webpage. As the user paves Firefox with the ruts of their Internet travels, Firefox starts populating the directory tiles with frequently and recently visited websites.

In place of the initially blank tiles, Mozilla's new directory tiles ad program will fill in the bald spots with content from "the Mozilla ecosystem… popular websites in a given geographic location, and… sponsored content from hand-picked partners to help support Mozilla's pursuit of our mission."

The rollout will not happen immediately. Darren Herman, vice president of content services, writes that the company is "beginning to talk to content partners about the opportunity and plan[s] to start sharing Directory Tiles to new Firefox users as soon as we have the user experience right."