Disclaimer

A Disclaimer is traditionally what one adds to the beginning of one's Fanfic. It usually runs along the lines of 'I do not own (this continuum) nor any of the characters therein' and then generally what passes for a funny joke, often about (author) turning in their grave and how much power it's generating. This joke is so prevalent that it led to the formation of the Department of Dead Author Electricity Generation.

As fanfiction hovers in a grey sort of area of legality that, essentially, people like to avoid talking about, a disclaimer is a polite nod to those who actually own a continuum. It is considered courteous to include one, and actually making it amusing gets you bonus points with readers.