Why Your Web Page Is In The Supplemental Index
The supplemental index, although preferable to the blacklisted wilderness, is not a place that you want your web pages indexed. Although a page has not been blacklisted it has not been deemed worthy to appear in the primary index and this can occur for a number of reasons. Pages languishing in the supplementary index may appear in the main results for a keyword but it is unlikely; fortunately, through good SEO practices, it is possible to climb out of the supplemental into the main index.
New SEO campaigns concentrate on the indexing and early ranking of web pages. In some cases, when a page has no inbound links or it uses duplicate content that appears on other websites, it may be possible that that page is only placed in the supplemental index. In this case, the most advantageous action is to undertake a proper SEO campaign. Conduct SEO keyword research, write high quality SEO content, and generate relevant SEO links for the pages.
Being banished to the supplemental index may not the be the ideal situation for a web page to be in, but there are far worse situations to find yourself in. While there is no effective way to appeal that a page be promoted to the primary index you should find through good SEO tactics that this will occur naturally and the speed in which pages are now crawled and indexed means that you only need to wallow in the supplemental pages for a relatively short space of time.