1. A method of extracting phrases from a corpus of documents, the method comprising: generating, by at least one processor, a set of candidate phrases from the documents in the corpus, wherein each candidate phrase corresponds to a group of two or more words that occur consecutively in at least one of the documents in the corpus, each candidate phrase having an occurrence count associated therewith; computing, by the at least one processor, a statistical metric for each candidate phrase based at least in part on the occurrence count, wherein the statistical metric indicates a likelihood of the words within the candidate phrase occurring consecutively by chance; selecting, by the at least one processor, a plurality of the candidate phrases as meaningful phrases, the selection being based on the statistical metric; computing, by the at least one processor, a phrase weight for each meaningful phrase, the phrase weight being based on a number of documents in the corpus that contain the meaningful phrase; and forming, by the at least one processor, clusters of the documents using the phrase weights.
8. The method of claim 1 , wherein the phrase weight for a meaningful phrase is based on 1/D, wherein D is the number of documents in the corpus that contain the meaningful phrase.