Trolling is a slang term for behaviour (generally online) designed to disrupt or de-rail online discussions – often for humorous effect, but sometimes more malicious in intent. Obvious examples include posting a deliberately controversial opinion in an attempt to goad readers into an angry response.

More recent use of the term has expanded to include sometimes criminal levels of offensive posting, designed to cause offense or upset to others. This has resulted in jail sentences for the worst offenders.