Microsoft's new version of its popular web browser now warns users about potentially untrustworthy news sources.

The service it uses is called NewsGuard — a third-party application run by journalists (including a Business Insider board member) who evaluate publications and rate them on a variety of factors.

Publications such as The Washington Post and Fox News are considered trustworthy, while warnings are issued for Breitbart, DailyKOS, The Daily Mail, and more.

Ever clicked on a news story only to discover that it's from some publication you've never heard of?

How did you determine if it was a trustworthy news source?

That problem is more prevalent than ever, as tens of millions of people get their news primarily from places like Facebook and Twitter.

Microsoft is aiming to tackle the problem with a major addition to its web browser: a built-in tool called NewsGuard that warns users before they click on a potentially untrustworthy news source.

The idea is simple: Users see a "Nutritional Label," similar to those seen on food products, that explains why the publication has been deemed trustworthy or untrustworthy.

The British tabloid Daily Mail is flagged as problematic because of credibility and transparency issues, according to NewsGuard. The Daily Mail/NewsGuard

The tool is rolling out to mobile users of Microsoft's Edge browser now, but is expected to head to other platforms in the future.

NewsGuard is also available as an extension for Chrome, Google's ubiquitous internet browser, and we used it to check the ratings of a variety of publications: