1. A system comprising: one or more devices to: determine, at a first time, a first set of topics relating to content within a document; determine, at a second time, a second set of topics relating to the content within the document, the second time being different than the first time; identify a change in a quantity of topics between the first set of topics and the second set of topics; generate a score for the document based on the change in the quantity of topics; and rank the document with regard to at least one other document based on the score.