According to University of Michigan Library, fake news is simply news stories that are false: the story itself is fabricated, with no verifiable facts, sources, or quotes.
There are four broad categories of fake news, according to media professor Melissa Zimdars of Merrimack College.
CATEGORY 1: Fake, false, or regularly misleading websites that are shared on Facebook and social media. Some of these websites may rely on “outrage” by using distorted headlines and decontextualized or dubious information in order to generate likes, shares, and profits.
CATEGORY 2: Websites that may circulate misleading and/or potentially unreliable information.
CATEGORY 3: Websites which sometimes use clickbait-y headlines and social media descriptions.
CATEGORY 4: Satire/comedy sites, which can offer important critical commentary on politics and society, but have the potential to be shared as actual/literal news
No single topic falls under a single category - for example, false or misleading medical news may be entirely fabricated (Category 1), may intentionally misinterpret facts or misrepresent data (Category 2), may be accurate or partially accurate but use an alarmist title to get your attention (Category 3) or may be a critique on modern medical practice (Category 4.) Some articles fall under more than one category. It is up to you to do the legwork to make sure your information is good.