Faceted search, also called faceted browsing, is a powerful technique that can speed up information retrieval and allow users to filter down quickly to the answers they need .

Mike Padilla explains that it "allows you to narrow down a large list of objects to a manageable size by applying flexible combinations of attribute filters in any order. Rather than forcing you down fixed paths within a website’s information architecture, faceted filtering allows you to multi-dimensionally slice-n-dice the information in a manner that best accommodates your specific needs"1. Implementations of faceted search exist in many online product catalogues like Amazon and Ikea Australia. Note from the image on the left that you can click the '+' sign next to any facet to expand it and further narrow your list of results.

Another intriguing example is the 'Elastic Lists Demo' which combines faceted search with data visualisation techniques. See http://well-formed-data.net/experiments/elastic_lists/

Screenshot of the Elastic lists demo with Nobel Prize winners

• Avoid having too many facets
• Use the 'more' link with long lists of facets and values
• Order facets and values based on relevancy rather than alphabetical order
• Create facets based on user behaviour and patterns
• Base your facets on a broad taxonomy
• Use a polyhierarchical taxonomy to ensure findability
• Usability is the most important test of a good faceted search interface!