5. The web site search and selection method as claimed in claim 1 , wherein the search engine uses a first file F_site_pages containing for each web site indexed by the search engine a total number of web site pages, the search engine also generating a second file F_Page_word for each word found in at least one page indexed by the search engine, each of said web sites having a field site_id.
7. The web site search and selection method as claimed in claim 5 , characterized in that the second file F_Page_word is organized as a sequence of triplets “site_id, page_id, relevance” arranged relative to the fields site_id and page_id, said triplets indicating, for each page, a relevance of the page relative to a word sought.