8. A computer program product, encoded on one or more non-transitory computer storage media, comprising instructions that when executed by one or more computers cause the one or more computers to perform operations comprising: receiving, at a search system from a user device associated with a user, user input comprising one or more characters of a partial search query; determining that the one or more characters of the partial search query correspond to a trigger query; in response to determining that the one or more characters of the partial search query correspond to a trigger query, determining a predicted query for the trigger query, the predicted query comprising the trigger query and additional information for refining the trigger query; and providing the predicted query to the user device for presentation to the user prior to the user submitting a search query to the search system.
8. A computer program product, encoded on one or more non-transitory computer storage media, comprising instructions that when executed by one or more computers cause the one or more computers to perform operations comprising: receiving, at a search system from a user device associated with a user, user input comprising one or more characters of a partial search query; determining that the one or more characters of the partial search query correspond to a trigger query; in response to determining that the one or more characters of the partial search query correspond to a trigger query, determining a predicted query for the trigger query, the predicted query comprising the trigger query and additional information for refining the trigger query; and providing the predicted query to the user device for presentation to the user prior to the user submitting a search query to the search system. 11. The computer program product of claim 8 , wherein in response to receiving the predicted query, the user device presents a search interface that prompts the user to select the predicted query, and wherein upon user selection of the predicted query, the user device submits the predicted query as a search query to the search system.