The Apachesolr module (7.x) allows us to build sites that use powerful search technology. Besides being blazingly fast, Apachesolr has another advantage: faceted search.
Faceted search allows our search results to be filtered by defined criteria like category, date, author, location, or anything else that can come out of a field. We call these criteria facets. With facets, you can narrow down your search more and more until you get to the desired results.