Faceted filtering is a mechanism that allows the user to progressively reduce a large group of items by selecting the desired attributes from various dimensions (or facets) of those items.
Wem diese Definition zu trocken ist, dem kann ich folgendes “Lehrvideo” empfehlen:
(via Whitney Hess)

es gibt da noch eine Variante in der Apple-Werbung
http://www.youtube.com/watch?v=sgoV4d7TFW8