Google Panda is the substantial algorithm change launched by in February 2011 with the objective to identify low quality pages and sites. These pages tend to contain text that is relevant to the query however may not be the best user experience. Panda has been implemented across all English language queries and has continued to make minor updated.
Implemented on all English Queries
Initially when Panda launched, it impacted only USA queries with accounts for around 12%. However, today the change is applicable for all English queries worldwide and it is expected that the impact would be similar for English speaking searchers across the world. This includes searches on Google.co.uk, Google.com.au as well as English queries in non-English speaking countries (searches on Google.fr with English results).
Utilizing searcher’s data about blocked sites
Google has always taken measures in determining relevant search results. The proof of this can be seen either on the pages itself (text on a page) or on the other sites (anchor text in links to a page). At times clues are also drawn from user behavior (how long the page takes to load by using toolbar data from users who access those pages). Even recently, Google has launched two ways of blocking particular sites from search results by the way of Chrome extension and block links directly in search results which appears once been clicked from results to a site and then return to search results.
Impact of the change
When launched large sites were affected as they have more traffic, pages, links and more signals available. According to the latest updates even smaller sites are facing the impact.