Supplimental Page

[AuroIN]

Supplemental pages are those pages that Google consider not important enough to include in their main index. They are not often crawled by search engine spiders. The main reasons why a page comes under supplementary result are

Duplicate Content
No content or Not Enough Content
Duplicate Title or Meta Tag
Very Deep Pages or URL Parameters
Orphaned Pages or Pages Having No Inbound Links

It is better to optimize such pages so that they don't come under supplementary results of SERP.