As much good stuff as there is on the Internet, unfortunately there is even more bad stuff such as spam, virii, scams, porn, crackers, etc. Another one of the annoying things found in abundance online are hoaxes. A hoax is usually an e-mail you receive with a supposedly very important message, urging you to pass this info on to as many people as possible to make them aware of this info. However, the message is bogus and passing it on will accomplish nothing else but create unnecessary junk e-mail messages, very similar to chain letters. The only purpose of hoaxes is to waste your time and make you help generate junk Internet traffic.
Hoaxes are essentially another type of virus.
Here's the big difference between a virus and a hoax. A lot of virii are malicious programs that spread themselves in secret by e-mailing themselves to some or all people in your address book without you even noticing. But a hoax is not a program or script and therefore cannot replicate and spread itself. It has to be a lot trickier.