17. The system of claim 14 , wherein each search context is associated with a respective group of users and a respective class of search queries.
17. The system of claim 14 , wherein each search context is associated with a respective group of users and a respective class of search queries. 19. The system of claim 17 , wherein the respective class for a particular search query is a query type determined in accordance with one or more of the terms of the particular search query.