20. The system of claim 19 , wherein the respective score for each of the one or more resources represents an indication of relative importance of the resource among the one or more resources specified in the context file by the content provider.
19. A system comprising: one or more computers and one or more storage devices storing instructions that are operable, when executed by the one or more computers, to cause the one or more computers to perform operations comprising: receiving, by a search system from a user device, a search query submitted by a user through a search interface of a website of a content provider; identifying, by the search system, a context file provided by the content provider, the context file identifying one or more preferences of the content provider for obtaining search results for users requesting searches through the search interface of the content provider, wherein the context file includes, for each of one or more resources, a respective score assigned by the content provider for the resource, the score representing a figure of merit of the resource relative to other resources identified in the context file by the content provider; obtaining, by the search system, one or more search results that satisfy the search query; ranking the one or more search results according to the respective scores assigned by the content provider in the context file; and providing the one or more search results to the user device for presentation to the user.