What is Filk?

• Something that's little enough known that every filk site has to have a "What is Filk?" page.
• Something that has rather more definitions than there are active filkers.
• Filking is a matter of Symbolism and Intent.
• Songs (and other things) performed by Science Fiction Fans (and others) at Science Fiction Conventions (and other places), usually about Science Fiction. Or Fandom. Or Spaceflight. Or Cats. Or Computers. Or Somebody Else's Song that they just did. Or Something Else. Or Something Even Elser. Or . . .
• There's a sort of semi-official definition here.
• And there's a whole lot of different definitions here
• And more pointers and discussion here
• And here's what the OED has to say.
• But lots of people would probably disagree with them all in various ways.