1. A method of refining descriptors associated with data items to enable retrieval thereof, comprising the steps of: storing said data items in both a summary form and in a complete form; receiving a search request from a user for selection of data items, said request incorporating at least one descriptor; sending the user a search result comprising only the summary form of data items selected in accordance with said search request; and using a response of the user requesting the complete form of a selected data item in the search result to guide modifications of the descriptors.