40. A search engine as claimed in claim 38 or 39 , including a cluster for processing indices output by said index network in response to said query, generating term frequency vectors for data indexed by said indices, comparing similarities between the indexed data on the basis of a distance between said frequency vectors and generating content based categories on the basis of said distances and placing the output indices into said categories for display.
40. A search engine as claimed in claim 38 or 39 , including a cluster for processing indices output by said index network in response to said query, generating term frequency vectors for data indexed by said indices, comparing similarities between the indexed data on the basis of a distance between said frequency vectors and generating content based categories on the basis of said distances and placing the output indices into said categories for display. 41. A search engine as claimed in claim 40 , wherein the feature extractor receives content features of said categories from said cluster and selects a unique descriptive feature for each category.