1. A computer-implemented method for determining a click distance associated with documents on a network, comprising: storing document and link information for the documents; within the document and link information, additionally storing a specialized word in association with a target document, wherein the specialized word designates a source document corresponding to the target document; including the specialized word in an inverted index, wherein the locally stored inverted index relates the specialized word with an identifier of the target document; and assigning a click distance to the source document when an inverted index is queried for the target document according to a query that passes in the specialized word.