Supplemental Index

In search engines, a supplemental index is comprised of Web results compiled with fewer restraints on sites than sites that are crawled for a main search engine index. Google is one search engine that uses both a main index and a supplemental index. In some instances restrictions for inclusion in the main index may be ignored allowing your Web site to be crawled by the supplemental index, or the supplemental index crawls those pages that the main index had difficulty with. Web pages that are listed in a supplemental index usually are not returned as results in Web search queries as often as those included by the main search index.