1. A method comprising: identifying, by one or more processors, a set of second documents, each second document, in the set of second documents, including a link to a first document; determining, by one or more processors and for each second document in the set of second documents, a time at which the link to the first document existed; assigning, by one or more processors, a freshness score to the first document based on the times at which the links to the first document existed; and ranking, by one or more processors, the first document, with respect to at least one other document, based on the freshness score assigned to the first document.