19. The method of claim 18 , further comprising: accessing query log data that includes queries submitted by users and the frequency with which each query was submitted; determining most likely sequences of initial query characters from the query log data; for each most likely sequence, determining most likely queries from the most likely sequence and the query log data, each most likely query having an initial sequence of query characters matching the most likely sequence of initial query characters; and designating the most likely queries determined for each of the most likely sequences of initial query characters as the initial query characters.
18. A computer-implemented method performed by a data processing apparatus, comprising: receiving from a client device a request for a search resource; and providing to the client device in response to the request for the search resource, the search resource including: first instructions that cause the client device to generate a search interface that includes a first query input field; initial query suggestions, wherein each initial query suggestion is determined from data separate from content of the search resource and, upon user selection from the search interface, is processed by a search service as a query, and wherein the initial query suggestions are provided to the client device with the search resource without an additional request for the initial query suggestions from the client device separate from the request; and second instructions that cause the client device to: store the initial query suggestions in a suggestion store on the client device; compare query characters input in the first query input field to the query suggestions stored in the suggestion store; select query suggestions that match the query characters input in the first query input field based on the comparison; and display the selected query suggestions as query suggestions for the query characters input into the first query input field.