Google’s supplemental index is to webmasters and bloggers what Samara from The Ring is to 13 year olds at a sleepover. It shouldn’t be - it isn’t something to be afraid of.

What The Google Supplemental Index Is

The supplemental index is where Google places URLs (pages) they deem unimportant. There are basically three reasons why Google would place a URL in the supplemental index.

1. Low PageRank
2. Little or no content
3. Duplicate content

Most of the results Google returns for keyword searches will be from their main index, but some will be from the supplemental index. It is 100% in your best interest to get as many pages as possible into Google’s main index. Click here to learn how to tell if your pages are in the supplemental index.

I have people every single week emailing me about my 358 pages that are in the supplemental index. Most of the time they offer solutions like robots.txt and the Duplicate Content Cure Plugin for Wordpress.

Almost everyone says to add ‘noindex’ to category, archive, and tag pages. These simple solutions would make it so that Google doesn’t index your category, archive, and tag pages, removing them from Google’s supplemental index. You can read where John Chow told everyone to do that exact thing here: Getting Out Of The Google Supplemental Index

Where Almost Everyone Is Missing The Boat About Google’s Supplemental Index

Google’s supplemental index isn’t a bad thing and URLs that are in the supplemental index won’t always be in the supplemental index. Panicking because you have some pages that are ’supplemental’ isn’t at all warranted, it’s straight up paranoia. It isn’t that big of a deal! Before you go axing all of your category, tag, archive pages, consider these numbers:

I have 638 total URLs in Google’s index, 358 of which are supplemental. This means that 280 of my URLs are in Google’s main index. Since I have only written 149 posts and am using 11 ‘pages’, I have 80 URLs in the main index that are category, archive, and tag pages. Is it really in my best interest to ax those URLs from Google entirely? I don’t think so. Instead of talking about how to remove URLs from the supplemental index, everyone should be talking about how to move them to the main index.

URLs can be moved from the supplemental index to the main index by increasing the PageRank of the URL (page) in question (see section below for details). If you want a real-world example of this you can have a look at all of ProBlogger’s URLs that are returned by searching for site:http://problogger.net in Google. If you look through all of ProBlogger’s URLs, you will see that all of his category pages are in Google’s main index. He doesn’t use date-based archive pages so we can’t really look at that. If you would have looked at his category pages back when he first started, do you think they would have been in Google’s main index? They wouldn’t have.

If ProBlogger would have axed those pages with a robots.txt or a fancy plugin would they be in the main index today? Nope. They would still be noindexed.

Here’s one more little factoid to consider before noindexing some of you pages. It is possible to get search engine traffic from a URL (page) that’s in the supplemental index. It isn’t possible to get search engine traffic from a URL that isn’t in either index.

Moving Pages From The Supplemental Index To The Main Index.

You will need to do three things in order to move pages from the supplemental index to the main index.

1. Work on the PageRank of your entire site, and for the URLs that are in the supplemental index. Matt Cutts (Google spokesperson to the SEO world) said on his blog, “Having urls in the supplemental results doesn’t mean that you have some sort of penalty at all; the main determinant of whether a url is in our main web index or in the supplemental index is PageRank.” This means you should link to those pages more, and you need more inbound links to your site. Here’s an article that can help you with that: Going From PR Zero To PR Hero - Most of Problogger’s category pages are PR5s. Pages that have PR1+ will likely be moved into the main index.
2. Add more content to the URLs (pages) in the supplemental index. Many pages are in there simply because they don’t have enough material on them. Adding content to those pages can help to get them moved out.
3. Reduce duplicate content. Make sure that your category and archive pages show excerpts instead of entire posts. Your posts will rank better than your category pages will anyway.

When I first started this blog, almost all of my posts ended up in Google’s supplemental index, so if you’re in that boat don’t worry about it. They will come out just like mine did.