Filk is music. Filk is fantasy. Filk is creativity.
Filk is mostly, but not necessarily, written and performed by amateurs and mostly, but not necessarily, deals with fantastic themes & lyrics that are mostly, but not necessarily, set to folk music.
If you still don't know what Filk is, you may find these pages helpful:
Here are some pages of German filkers:
Katy's links to German Filkers
Ju & Katy - Internationally known Filkduo with ironic and poetic songs, mainly in English
Steve MacDonald - Imported from the US; cool songs and incomparable stage presence
Thesilee - Beautiful and sinister songs in German and English
Sibs Seite - A few of Sib's Songs, her Blog, photos und more (in English)
Sagensang - Lively songs and parodies ranging from Science Fiction to Medieval
GeBorgt - Many-voiced and multifaceted Filk group
Die Schattenweber - Very atmospheric Medieval and Filk band
Lord Landless - Thesilee's and Silva's (Schattenweber) former band