The Supplemental Index: What is it? Why is it bad?
In terms of trust and rank, Google has two indexes in which it categorises web pages.
- The Main Index
This is the set of web pages Google ranks and trusts. These pages are those which appear in SERPS for competitive keywords.
- The Supplemental Index
Pages in this index are not trusted or have little or no rank. Pages in this index will not appear in SERPS for any but the most specific search phrases, e.g. a phrase like “yellow-feathered fish riding a bicycle” which is unlikely to appear on any other web page.
Needless to say it is better to have the pages on your website in the main index.
So, how can you tell if pages on a site are in the main or supplemental index?
Historically, there were two ways of finding whether a page was in the supplemental results. Note that neither of these two methods work any more.
- The site: operator could be used. You used to be able to type a command into Google in the format:
site:www.yoursite.com *** -sljktf
(replacing www.yoursite.com with the URL of the domain you wanted to check). A list of supplemental pages on the domain would then be returned.
- Google used to label supplemental pages in SERPS as “Supplemental Result” but this has now been removed. See Supplemental Results Update for more info.
So what works today?
Nowadays you still seem to be able to find the most “important” pages on a site using the command:
site:www.yoursite.com/*
You can then compare the list returned with the complete list of indexed URLs on a site returned by:
site:www.yoursite.com
Any URLs returned by the second command that aren’t returned by the first are probably supplemental.