Trolls are imaginary creatures in Scandinavian folklore who are dim witted, live far from human company, and are generally unpleasant when encountered. In modern slang the word refers to individuals who make themselves disagreeable on social media by persistently responding to other people’s posts in negative ways, ranging from discourtesy to threats and intimidation. If you write for the medical press and try to maintain a social media presence it’s almost impossible to avoid trolls. Some topics are guaranteed to bring them out in battalions.