The understanding people have of the supplemental index is still evolving, informed partly by limited explanations of how it works from Google, both official and unofficial. However, there are certain features that have become clear and that you need to be aware of:
- Pages that trigger spam filters are more likely to be removed from the index altogether than to be placed in the supplemental index; the supplemental index is not a form of penalty that can be lifted through requests to be reincluded.
- Pages in the supplemental index are less likely to be returned to users undertaking a search and less likely to be ranked well in the search results served to users.
- Pages are very likely to end up in the supplemental index if they closely match pages elsewhere on your site (so-called duplicate content).
- Pages may end up in the supplemental index if they closely match pages on other sites that are cited more often than yours (i.e., where you appear to have syndicated – or even plagiarized – content).
- Pages from very large sites may end up in the supplemental ndex if insufficient PageRank has been passed to the page
- Pages that are hard to crawl (e.g., because they use too many parameters in a URL or are larger than 101k) may end up in the supplemental index.
- According to Google’s unofficial spokesperson Matt Cutts, the pages held in the supplemental index are parsed differently and held in the form of a “compressed summary,” meaning that “not every single word in every single phrase relationship” has been fully indexed.
Click here to see how to counter the effects of the supplemental index.
How Google stores the index
Know how google works can help webmaster to understand how to improved website.
Counter the effects of supplemental index
There are steps you should take to counter the effects of the supplemental index
How to check the supplemental index?
There are some simple step to find out which of your pages are in the supplemental index.