Mozilla to sell New Tab page ads in Firefox

Called Directory Tiles, the initiative will use a combination of sponsored sites, popular sites based on geographic location, and Mozilla ecosystem items to fill in blank New Tab pages. Currently, the nine empty boxes on a new New Tab page fill in over time with sites culled from the user's browsing history, frequently visited sites, and bookmarks.

Once the user has browsed enough to satisfy the needs of the "frecency" algorithm, which combines the frequency and recency with which the user visits a Web site, the Directory Tiles will be automatically replaced with content more relevant to the user. Herman said that this period is generally between 30 and 45 days for most new users.