If you ran a website around 2006, you probably remember the fear of the word "Supplemental Result." You typed site:yourdomain.com into Google, scrolled down, and saw that tag next to page after page. Forums called it "supplemental hell." A Forbes article later called it "Google Hell." Many owners believed those pages had been penalized.
The truth was less dramatic but still important. Let me explain what the supplemental index really was, what changed in late 2006, how Google explained it, and why the same worry lives on today in Search Console's "Crawled – currently not indexed" status.
For context on everything that came before and after, see our full timeline of Google algorithm updates.
The supplemental index update at a glance
| Question | Answer |
|---|---|
| When | Late 2006 into early 2007. SEOmoz's update list dated it November 2006; Barry Schwartz's list used January 2007 |
| Type | Indexing change, not a ranking penalty |
| Confirmed by Google? | Partly. Google staff discussed the supplemental index publicly in November 2006 and January 2007, but there was no announced "update" |
| What changed | More pages were reported moving into the supplemental index; site: results began showing regular pages ahead of supplemental ones |
| Main cause, per Google | Not enough PageRank to be in the main index |
| Who was affected | Sites with many low-linked, duplicate or parameter-heavy URLs: ecommerce filters, tag pages, thin directories, sites whose link value fell after Jagger and Big Daddy |
| What happened next | The "Supplemental Result" label was removed in July 2007; Google said in December 2007 it was searching the whole index for every query |
What the supplemental index actually was
Think of Google's index as a huge library. In 2003, Google added a second, bigger storeroom behind the main library. Pages in the main library were checked for almost every search. Pages in the storeroom were only pulled out when the main library didn't have enough good answers, usually for rare or very specific searches.
That storeroom was the supplemental index. Wikipedia's timeline dates its announcement to September 2003. Years later, Google's Yonatan Zunger described the original purpose this way:
“a 'supplemental index' as a way of showing more documents to users”
— Yonatan Zunger, Google, The Ultimate Fate of Supplemental Results
So the original idea was positive. Google could keep more pages without slowing down every search. The problem for site owners was practical: a page in the supplemental index rarely showed up for competitive searches, and it was crawled less often. In the 2007 post Supplemental goes mainstream, Google said the index often held pages with lower PageRank or more complex URLs.
What changed in late 2006
This is where the record gets thin, and I want to be clear about it. Google did not announce a "Supplemental Index Update." The name comes from SEO update lists. Search Engine Roundtable's roundup of update lists shows SEOmoz dating it to November 2006, while Barry Schwartz's own list says January 2007. Both lists were built from forum reports.
Here is what we do know from that period:
- Big Daddy had just finished. Google's new crawling and indexing infrastructure completed around March 2006. Search Engine Journal's Big Daddy history notes that supplemental index changes were happening while Big Daddy was in full swing, and that forum threads often mixed the two up.
- Many site owners reported more pages going supplemental. Category pages, tag pages, product variations and duplicated content were common examples.
- Google talked about it in November 2006. On November 20, 2006, Search Engine Roundtable reported on Google's comments, including Adam Lasnik's explanation that these pages lacked enough PageRank for the main index.
- Google changed site: results in January 2007. Matt Cutts wrote that regular results would usually appear ahead of supplemental ones for site: queries.
Barry Schwartz summed up the mood well. Google said supplemental status wasn't harmful, yet suggested more links as the "cure." He wrote that the more Google explained, "the more confused SEOs are, including myself" (Confusion Over Google's Supplemental Index).
How Google explained it: PageRank, not penalties
The clearest explanation came from Matt Cutts in his Infrastructure status, January 2007 post. He made three points that he repeated many times afterward.
“the main determinant of whether a url is in our main web index or in the supplemental index is PageRank.”
— Matt Cutts, Infrastructure status, January 2007
- It is not a penalty. He wrote that "supplemental results aren't something to be afraid of."
- PageRank decides placement. Pages without enough link value drop into the supplemental index.
- A move can signal weaker links. If pages that used to be in the main index moved to supplemental, links pointing to the site might be counting for less than before. His advice was to earn better links.
That third point connects this story to the Jagger update of 2005. If Google stopped counting reciprocal swaps and paid links, a site's PageRank fell. Lower PageRank meant fewer pages qualified for the main index. In May 2007, replying to a Forbes article titled "Condemned To Google Hell," Cutts pointed to a site's heavy reciprocal linking as a likely reason its pages had gone supplemental (Google Hell?). Search Engine Watch called the Forbes piece fear-mongering.
Signs a page was supplemental, and what caused it
In 2006, checking was simple: search site:yourdomain.com and look for the green "Supplemental Result" text under a listing. Most owners also noticed these patterns:
- The page's cached copy was weeks or months old.
- It ranked only for very long, exact phrases, never for its main keyword.
- Pages showed up at the end of site: results, after normal ones.
Common causes, based on Google's explanations and forum reports:
| Cause | Why it pushed pages supplemental | Typical fix at the time |
|---|---|---|
| Low internal and external PageRank | Deep pages linked from nowhere except a sitemap had little link value | Better internal linking; earn links to key sections |
| Duplicate content | Printer versions, session IDs, www and non-www copies split value across many URLs | 301 redirects; one URL per page |
| Parameter-heavy URLs | Filters and sort options created thousands of near-identical pages | Block or consolidate filter URLs |
| Thin pages | Tag pages, empty categories and boilerplate product pages added little | Merge, improve or noindex them |
| Lost link value | Swapped or bought links were discounted after 2005 | Earn editorial links |
The canonical tag didn't exist yet. It arrived in 2009. So in 2006, fixing duplicates meant redirects, robots.txt and cleaner site architecture.
A worked example
Example (hypothetical): a 2006 shoe store has 300 products. Each product can be sorted by price, color and size, and each sort creates a new URL. That turns 300 products into roughly 3,000 crawlable URLs. The store has 50 good backlinks, mostly to the home page. Spread across 3,000 URLs, the link value reaching each product page is tiny.
The likely result: the home page and main categories stay in the main index, while most product and filter URLs go supplemental. Cut the filter URLs and link products from their categories, and the same 50 links now support 300 pages instead of 3,000. That is a tenfold improvement in how far the link value has to stretch. The same logic applies to crawl budget today.
Google retires the label, then the separate index
The supplemental story ended in two steps in 2007.
July 31, 2007: in Supplemental goes mainstream, Prashanth Koppula and Matt Cutts said Google had overhauled supplemental crawling and indexing since 2006. They reported that supplemental results were fresher and more complete, that URLs with more parameters could be handled, and that more queries would search the supplemental index. Then they removed the label.
“The distinction between the main and the supplemental index is therefore continuing to narrow.”
— Google Webmaster Central Blog, Supplemental goes mainstream
December 2007: in The Ultimate Fate of Supplemental Results, Yonatan Zunger wrote that Google had separated crawl frequency from index placement and was phasing out the distinction between indexes. His key line: "we're now searching the whole index for every query."
It was a busy year for Google's index. Two months before the label went, Universal Search launched in May 2007 and began blending news, images and video into web results. A month later, forums reported the Buffy update of June 2007. After that, the term "supplemental" faded. A few years later, Caffeine in 2010 rebuilt Google's indexing system again.
Modern equivalents in Search Console
The supplemental index is gone, but the worry behind it hasn't disappeared. Today the question is not "main or supplemental?" but "indexed or not?" The Search Console Page indexing report is where you see it. Several statuses play the role the supplemental label once did.
| 2006 concern | Closest 2026 status | Google's description |
|---|---|---|
| Low-value pages stuck outside the main index | Crawled – currently not indexed | "The page was crawled by Google but not indexed." |
| Duplicate URLs splitting value | Duplicate without user-selected canonical | "This page is a duplicate of another page, although it doesn't indicate a preferred canonical page." |
| Google ignoring your preferred version | Duplicate, Google chose different canonical than user | Google thinks another URL makes a better canonical |
| Deep pages rarely crawled | Discovered – currently not indexed | Google knows the URL but hasn't crawled it yet |
Descriptions are quoted from Google's Page indexing report help page. If you're seeing many pages in these buckets, our guides on fixing Crawled – currently not indexed and duplicate content causes and fixes go deeper. For beginners, the lesson on getting pages indexed covers the basics.
The lesson from 2006 carries straight over. Pages with little link value, little unique content and many duplicates are the ones search engines care least about. This is also what the Mayday update in 2010 later hit on the long-tail side.
Here is a quick check I suggest after any big change in indexing:
- Open the Page indexing report and note the counts for each "not indexed" reason.
- Compare them with the same report from a month earlier.
- Open sample URLs in each reason and look for patterns: filters, tags, thin templates.
- Check the Crawl Stats report to see whether Google is crawling less. Our guide on checking crawl stats after an update shows how.
- Fix the pattern, not single URLs: consolidate duplicates, improve thin templates, strengthen internal links.
Questions site owners asked about supplemental results
Was being in the supplemental index a penalty?
No. Google said repeatedly that it wasn't. It was a sign that a page didn't have enough PageRank to make the main index. But since supplemental pages rarely ranked for competitive searches, it felt like a penalty to many owners.
Was there an official "Supplemental Index Update"?
No. The name comes from SEO update lists that dated it to November 2006 or January 2007. Google discussed the supplemental index in that period but never announced a named update.
Does the supplemental index still exist?
Not as a separate, labeled index. Google removed the label in July 2007 and said in December 2007 that it was searching the whole index for every query.
What is the modern version of going supplemental?
Pages showing as "Crawled – currently not indexed" or as duplicates in Search Console's Page indexing report are the closest equivalent today.
Turning supplemental-era lessons into an indexing plan
The supplemental index taught site owners that Google won't treat every URL equally. The pages that get attention are the ones with real links, real content and one clean address. That was true in 2006 and it is true now, just with different labels.
If a big part of your site isn't getting indexed, we can help you find out why. See our SEO services, or get a free quote and we will take a look.
Google updates around the same time
Before this update:
- Big Daddy (2005-2006): Google's Infrastructure Update Explained (Dec 2005)
- The Jagger Update (2005): Google's Three-Part Attack on Link Schemes (Sep 2005)
After this update:
- Google Universal Search (May 2007): Blended Results and the End of Ten Blue Links (May 2007)
- The Buffy Update (June 2007): A Bundle of Small Changes (Jun 2007)
Or browse every Google update on one timeline, newest first.
Sources for this supplemental index history
- Search Engine Roundtable: Confusion Over Google's Supplemental Index (November 20, 2006)
- Matt Cutts: Infrastructure status, January 2007
- Matt Cutts: Google Hell? (May 1, 2007)
- Search Engine Watch: Forbes Spreads Supplemental FUD
- Google Webmaster Central Blog: Supplemental goes mainstream (July 31, 2007)
- Google Webmaster Central Blog: The Ultimate Fate of Supplemental Results (December 2007)
- Search Engine Journal: Google Big Daddy Update
- Search Engine Roundtable: Google update lists
- Wikipedia: Timeline of Google Search
- Google Search Console Help: Page indexing report
