1. A computer-implemented method comprising: identifying a plurality of documents, from a set of documents, wherein each of the plurality of documents include a top N terms, wherein the top N terms are the same for each of the plurality of documents, wherein the top N terms are based on respective term frequency scores, and wherein N is an integer; identifying at least a subset of the identified documents that satisfy a pattern string; and forming a document cluster from at least the subset of the identified documents.
8. The method of claim 1 , wherein the pattern string comprises a string that is satisfied by Universal Resource Locators of the documents in the subset of the identified documents.