Although some fake news stories are satirical and not intended to be taken seriously, others purposefully aim to do harm. Some stories circulate for only a short time, then fade away without causing much damage. Others cause long-term harm. If it is left unchecked, fake news can have dangerous ramifications. It can undermine democracies, amplify racial tensions, negatively impact public health, and destroy businesses and reputations. To combat fake news, people must be vigilant. It is important that everyone check the validity of information before passing it on to others. In this manner, every person can help make the world safer.

Introduction: A far-reaching problem -- What is fake news? -- Denying science -- Stoking divisiveness -- Combating fake news.