15. A non-transitory computer-readable storage medium having computer-readable instructions stored thereon, the computer-readable instructions comprising: one or more instructions to receive history data for a document, the history data comprising an appearance date for each of a plurality of links to document; one or more instructions to determine, from the history data, that there has been a decrease in a rate or quantity of appearances of new links that point to the document over time, and then classify the document as stale, the one or more instructions to determine that there has been a decrease in the rate or quantity of appearances of new links that point to the document over time, including: one or more instructions to compare an oldest appearance date, of the appearance dates of the links to the document, to an oldest appearance date of the appearance dates of a group of newest links to the document, each link in the group of newest links to the document having an appearance date that is within a percentage of most recent appearance dates of the links to the document; one or more instructions to decrease, based on classifying the document as stale, an initial score for the document, resulting in an altered score; and one or more instructions to rank the document with regard to at least one other document based on the altered score.
16. The non-transitory computer-readable storage medium of claim 15 , where the computer-readable instructions further comprise: one or more instructions to receive a search query, where the document and the at least one other document are responsive to the search query; and one or more instructions to present the document and the at least one other document according to the ranking.