Fact checkers work in journalism to correct errors in nonfiction writing. They are usually hard at work behind the scenes in mainstream media, particularly newspapers and magazines, investigating the work of journalists to make sure an article accurately reflects the facts before it is published. In recent years, online fact-checking organizations have popped up to counter the spread of misinformation facilitated by the internet.
When you are reading a document and want to make sure it's credible, do as a fact checker does and read laterally. This means to open a new tab and do a search for the publisher/website, the author, the facts of the story. How is the issue described elsewhere? What kind of reputation does the publisher or website have? What else has the author written or created?
The value of lateral reading in debunking false claims is discussed in this article:
The Duke University Reporters' Lab tracks fact-checking organizations across the world and collects news about fact-checking.
How to Spot Fake News infographic by the International Federation of Library Associations and Institutions (IFLA), 2017