The Firefox browser includes a secret filter that prevents adult sites from showing up on the new tab page, and by doing so, exposing some users' unsavory web browsing habits to nearby friends, to shoulder-surfing strangers, or in the worst case scenario -- to the media.
The filter isn't new, dating back to , but has only recently been spotted by some keen-eye Redditors, in November and today. This means that any time a user makes a habit of visiting a particular adult site, or the user intentionally or accidentally bookmarks an adult page, that page won't show up on the New Tab page at the most imappropriate times.
The reasons behind this filter don't reside in the engineers' attention to protecting users' browsing habits and privacy, but in sheer commercialism.
The filter was developed and implemented back in Back then, the Firefox New Tab page contained a section called Suggested Tiles, which was used as a way to show sponsored content and to surface some of users' most visited sites. Mozilla devs implemented the adult filter because commercial partners that bought sponsored content didn't want their tiles "to be negatively associated with adult content.
The original adult filter list wasn't the only blacklist that Firefox implemented for the New Tab page back in Devs also included other blacklists, like the one for preventing thumbnails of piracy and torrent sites from being shown next to tiles promoting official DVDs.
