1. A computer-implemented method, performed by one or more computing devices, for generating and transmitting search results responsive to a user search query from a user, the method comprising: receiving the user search query comprising one or more search terms; obtaining candidate search queries for the user search query, the candidate search queries corresponding to modifications of the one or more search terms; obtaining candidate scores for the candidate search queries, wherein a candidate score for one of the candidate search queries corresponds to a probability that the one of the candidate search queries is an effective replacement for the user search query; initiating a search for online resources relevant to the one or more search terms; initiating searches for additional online resources relevant to the candidate search queries; obtaining user interaction scores, wherein the user interaction scores are based on user interactions with the online resources and the additional online resources; based on the candidate scores and the user interaction scores, generating a search results list including search results that comprise one or more of the online resources and one or more of the additional online resources; incrementing the candidate scores for the candidate search queries associated with the one or more of the additional online resources included in the search results list; and transmitting the search results list as a response to the user search query.
10. The computer-implemented method of claim 1 , further comprising: receiving an indication of an interaction of the user with at least one of the search results on the search results list; and storing data associated with the interaction of the user with the at least one of the search results on the search results list.