Excellent article from Vanessa Fox of Search Engine Land outlining how Google’s latest update impacts various sites.
I asked Google for more specifics and they told me that it was a rankings change, not a crawling or indexing change, which seems to imply that sites getting less traffic still have their pages indexed, but some of those pages are no longer ranking as highly as before. Based on Matt’s comment, this change impacts “long tail” traffic, which generally is from longer queries that few people search for individually, but in aggregate can provide a large percentage of traffic.
This change seems to have primarily impacted very large sites with “item” pages that don’t have many individual links into them, might be several clicks from the home page, and may not have substantial unique and value-added content on them. For instance, ecommerce sites often have this structure. The individual product pages are unlikely to attract external links and the majority of the content may be imported from a manufacturer database.
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