1. A method of providing to a user an interactive product search facility suitable for searching product information stored in a product catalog, the method comprising the steps of: (a) providing a database of records respectively describing products, each of said records including a plurality of fields containing respective field values which characterise said products; (b) receiving from a user a request to search said database of records in the form of a query based on one or more of said fields; (c) providing to the user an initial set of similar search records found as a result of a similarity search based on said search request; (d) receiving from the user relevance feedback as to which of said similar search records are of greater and/or lesser relevance to the user compared with other similar search records; and (e) providing to the user a modified set of similar search results found as a result of a similarity search based on (i) said search request, and (ii) said relevance feedback, said modified set of similar search results providing to the user records which are generally of greater relevance to the user than said initial set of similar search results.