1. A computer-implemented method comprising steps of: receiving an original question from a user; generating two or more queries based on the original question; submitting each of the two or more queries to a search engine; for each particular query of the two or more queries, receiving, from the search engine, a separate search engine result for that particular query, thereby receiving a plurality of search engine results; wherein the search engine result for each particular query corresponds to a separate document set; wherein the plurality of search engine results correspond to a plurality of document sets; generating a single concept set based on terms in documents from the plurality of search engine results; wherein the single concept set is generated by, for each search engine results in the plurality of search engine results, identifying terms in documents from the search engine results, and adding at least a subset of said terms to said single concept set; using the single concept set to determine how to respond to the original question by performing at least one of: generating a refined set of search results for the original question based on the single concept set, and returning the refined set of search results as a response to the original question; or using the single concept set to identify questions similar to the original question; wherein the steps are performed by one or more computing devices.