If you don’t know what supplemental results are, and you want to learn, this is what Google says about it:
“Supplemental sites are part of Googleâ€™s auxiliary index. Weâ€™re able to place fewer restraints on sites that we crawl for this supplemental index than we do on sites that are crawled for our main index. For example, the number of parameters in a URL might exclude a site from being crawled for inclusion in our main index; however, it could still be crawled and added to our supplemental index.
The index in which a site is included is completely automated; thereâ€™s no way for you to select or change the index in which your site appears. Please be assured that the index in which a site is included does not affect its PageRank.”