No, the Reese’s Peanut Butter Cup is not being discontinued. No, Earth will not be plunged into darkness for 15 days. And, no, Katy Perry did not broker peace with the Islamic State.

Those are a few of the falsehoods spread online that are in need of debunking in this age of “fake news,” when misinformation seems to appear from nothing and reaches hurricane-force speeds in an instant.

Researchers have spent decades trying to understand how such misinformation spreads and, now, a review of their work offers new guidance for the journalists, fact-checkers and others working to find, and defend, the truth.