• by Wendy Davis , Staff Writer @wendyndavis, December 8, 2015

In a move aimed at enabling Web users people to wield more control over their data, Mozilla today released a new ad-blocking app that prevents companies from tracking people on their iPhones and iPads.

"We want to build an Internet that respects users, puts them in control, and creates and maintains trust." Denelle Dixon-Thayer, chief legal and business officer at Mozilla, writes in a blog post. She adds that the new app, Focus by Firefox, "allows users to control their data flow by blocking categories of trackers such as those used for ads, analytics and social media."

Unlike some popular iOS ad blockers, Focus will be free, Dixon-Thayer writes. It also will only block ads with trackers.

The company's move comes one month after it released a new no-tracking setting for Firefox. That tool, the "Private Browsing with Tracking Protection" setting, "actively blocks content like ads, analytics trackers and social share buttons that may record your behavior without your knowledge across sites," Nick Nguyen, vice president of Firefox Product, wrote in a blog post.

Mozilla issued the new iOS app just days after saying it will end the "sponsored tiles" behavioral advertising program for Firefox. That program categorized Firefox users based on their browsing history, and then showed them "tiles" from marketers who wanted to reach specific segments.

Mozilla consistently touted the "tiles" program as privacy-friendly, noting that users could edit and delete their browsing history, and could also opt out of the program altogether. Still, it always seemed curious that Mozilla was offering a behavioral-targeting ad program while simultaneously releasing ad-blocking tools.

Focus by Firefox works by preventing ad networks and other third parties -- including social media companies that place widgets on other publishers' sites -- from serving ads or collecting data from consumers. Mozilla's list of trackers comes from Disconnect, which defines tracking as collecting and retaining data regarding users' activity across more than one site or app.

It's not yet known whether users will embrace Focus the way they flocked to other ad blockers, like Peace -- a $2.99 app that was pulled just two days after it launched in August.

That app licensed Ghostery's list of around 2,000 domains that serve third-party ads and trackers. Peace then prevented those domains from loading scripts on users' devices. Ghostery CEO Scott Meyer said at the time that his company, together with Peace's developer, Marco Arment, decided to discontinue the app because it was used in a way that "compromised the neutrality that Ghostery is built on."