A facet is an index field that represents a category that you want to use to refine and filter search results. When you submit search requests to ASN Search, you can request facet information to find out how many hits share the same value in a particular field. You can display this information along with the search results and use it to enable users to interactively refine their searches. (This is often referred to as faceted navigation or faceted search.) See the faceted search demo application as an example.
You can get facet information for any uint field and facet-enabled text and literal fields by specifying the facet parameter in your search request.
ASN Search also provides search parameters that enable you to control how facet values are returned and sorted. You can select which facets to retrieve, limit the number of facet values returned, and control the sorting of the facet values for each field.