Google's "supplemental" index

what causes it?

[Clark]

Has anyone found the Google "Supplemental" index just from a regular search? Any ideas on how it works?

[keeper]

Do you mean the "- Supplemental Result" that sometimes appears between the page size figure and the "cached" link?

I just saw it for the first time today. Google's explanation of the feature is not exactly crystal clear is it?

Perhaps they keep a cache of low quality pages they don't want in the mix for mainstream search, but kick them in to answer low volume searches..

And who knows what low quality means to Google ;)

[mcavic]

[webmasterworld.com ]

[Clark]

There's a little bit here [searchenginewatch.com...] (I'm assuming Danny Sullivan links are OK since he's been around for so long and his articles make news in SEO world?)