What is a "filk"?

Filk -- I have seen this word used twice in as many days online. It seems to mean a tribute song or parody written by a fan.

specifically a fan of science fiction or fantasy; one of my brothers occasionally writes filk songs.

The term "filk song" originated from a straight forward essay, "The influence of science fiction on modern American filk songs" by Lee Jordan in the late 1950s. Filk was a typographical error (more commonly referred to now as a typo) for folk.

The article was rejected for publication. But the quirky label remained and applied to a musical event at a science fiction convention. Over the past 50 years, filk singing has grown in popularity.

For further details:
www.geocities.com/ Area51/Dimension/3511/filkhist.html