16. The computer readable memory device of claim 15 , the operations further comprising: receiving search results, each search result referencing a resource and including a snippet of text extracted from the resource; processing the search results to extract data to store in the search history data; and storing the extracted data in the search history data.
15. A computer readable memory device storing instructions that cause a data processing apparatus to perform operations comprising: receiving, in response to a selection of a search result referencing a first webpage resource, content of the first webpage resource, wherein the first webpage resource is determined to be responsive to a search query included in a search request, the search query being one or more terms that are submitted to a search engine as input to a search operation, and the search result having been provided in response to the search request; receiving a candidate set of search query suggestions for the search query, each search query suggestion in the candidate set being one or more terms that may be submitted to a search engine as input to a search operation, the candidate set of search query suggestions based, in part, on search history data that includes data from and related to previous search requests associated with the search query; for each of the search query suggestions in the candidate set of search query suggestions that meet a relevancy criterion that defines the search query suggestion as being relevant to the content of the first resource, the relevancy criterion being a relevance score that measures a relevance of the search query suggestion to the content of the first webpage resource displayed on a user device, including the search query suggestion in a final set of search query suggestions so that the final set of search query suggestions include only search query suggestions that meet the relevancy criterion; and providing the final set of search query suggestions for display on the user device.