A hoax is a fake warning about a virus or other piece of malicious code.
Typically a hoax takes the form of an e-mail or other message warning the reader of a dangerous new virus and suggesting that the reader pass the message on.
Hoaxes cause no damage in themselves, but their distribution by well-meaning people often causes fear and uncertainty.
Many anti-malware vendors include hoax information on their web sites and it is always advisable to check before forwarding warning messages.