Filtering search results with facets
The real power of the Apache Solr search technology comes into play when users only have a broad idea of what they are looking for when starting a search.
Search facets, also known as filters, are a part of the Solr search technology powering Acquia Search. They allow users to refine or sort their search result set. Users can begin with a general search and narrow down the result set as they understand better what content is available on your site.