Urban Legends & Internet Legends
Urban Legends are tales that are told and re-told, changing as they go to match the time and place they are told in.
Internet Legends are urban legends that originate and grow almost exclusively on the Internet. Since the start of the world wide web, there have been more than a few stories that have begun in emails and webpages and spread from there, and they can be infuriatingly hard to follow back to sources... especially when websites can go away and people use nicknames to hide their identities. Nonetheless, enough has come into existence that this must be acknowledged as a phenomena.
Not surprisingly, these two sources for stories can also often get mixed together, with a new Internet Legend being spawned by reports of an Urban Legend, or an Urban Legend beginning with something someone read on the internet.
Legends of these types change often, to match the interests of both the tellers and the listeners; but they can also be based on real reports, or blend in a confusing way with events that resemble the legends and then get intertwined. In most cases, it will be forever impossible to find any real events that may have started one of these legends; but in all cases they are living illustrations of the weird sorts of things that people believe should happen.