1. A method performed by a computer for clustering a plurality of documents in a hierarchical data structure comprised of a plurality of clusters, wherein each document includes a plurality of words, the method comprising: accessing the document collection; performing a clustering process that creates a hierarchy of clusters that reflects a segregation of the documents in the collection based on the words included in the documents, wherein any document in the collection may be assigned to a first cluster in the hierarchy based on a first segment of the respective document, and the respective document may be assigned to a second cluster in the hierarchy based on a second segment of the respective document, wherein the first and second clusters are associated with different paths of the hierarchy; storing a representation of the hierarchy of clusters in a memory; and making the representation available to an entity in response to a request associated with the document collection.