Reverse question answering

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for associating each of a plurality of different terms to documents that contain the term to create first associations; associating each of the associated documents to one or more queries to create second associations, wherein search results for each of the queries include a reference to the associated document; determining a particular query and a particular term are associated with a same document based on the first and second associations; in response to the determination, creating a mapping between the particular query and the particular term when both are associated with the same document; and selecting a respective answer from a plurality of mapped terms for each the mapped queries, wherein the respective answer is selected based on a count the respective answer occurs in documents contained in search results for the mapped queries.