1. A machine-readable medium having no transitory signals and in storing instructions which, when executed by the at least one processor of a machine, cause the machine to perform operations comprising: detecting entry of a first keyword of a search string comprising a plurality of keywords; identifying the first keyword of the search string, the identifying of the first keyword occurring after entry of the first keyword and prior to entry of a second keyword of the search string; in response to the identifying of the first keyword, determining a first set of matching results that match the first keyword; detecting entry of the second keyword of the search string; identifying the second keyword of the search string; using the second keyword, refining the first set of matching results that match the first keyword to obtain search results for the search string; and causing presentation of the search results.