1. One or more computer storage media storing computer-executable instructions for performing a method for identifying related strings for search query rewriting, the method comprising: accessing click log data; identifying session data for a user search query session in the accessed click log data, the session data including: a first user search query, search results provided for the first user search query, one or more additional search queries, and search results provided for the one or more additional search queries; determining whether a first additional search query in the session data is related to the first user search query based on at least one of: dwell time, a number of search result links clicked on, and similarity between web page titles or uniform resource locators (URLs); and upon determining that the first additional search query is related to the first user search query, incorporating the first additional search query into a list of strings related to the first user search query.