4. The method of claim 1 , wherein each query in the plurality of queries was issued and received at a web search engine previous to the particular query.
4. The method of claim 1 , wherein each query in the plurality of queries was issued and received at a web search engine previous to the particular query. 24. A volatile or non-volatile machine-readable medium storing one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 4 .