1. A method for automatically discovering a hierarchy of concepts from a corpus of documents, the concept hierarchy organizes concepts into multiple levels of abstraction, the method comprising: a. extracting signatures from the corpus of documents; b. identifying similarity between signatures; c. hierarchically clustering related signatures to generate concepts and hierarchically clustering concepts thus generated, whereby hierarchical clustering obtains a concept hierarchy; d. labeling the concepts organized in the concept hierarchy; and e. creating an interface for the concept hierarchy generated.