1. A method of query classification, the method comprising: receiving one or more seed documents that correspond to a category; receiving at least one query click log containing information regarding queries entered by at least one user into at least one search engine and documents clicked in search engine results corresponding with the queries; determining, based on information contained in the at least one query click log, one or more queries that resulted in at least one click on the one or more seed documents; and storing information associating the one or more queries with the category.