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Google algorithm • Panda • Penguin • Hummingbird • Pigeon • Mobile • Rank Brain • Possum • Fred
Panda • February 24, 2011 • Duplicate • plagiarized or thin content • user-generated spam; • keyword stuffing
Penguin • April 24, 2012 • Spammy or irrelevant links • links with over-optimized anchor text
Hummingbird • August 22, 2013 • Keyword stuffing • low-quality content
Pigeon • July 24, 2014 (US); • December 22, 2014 (UK, Canada, Australia) • Poor on- and off-page SEO
Mobile • April 21, 2015 • Lack of a mobile version of the page • poor mobile usability
RankBrain • October 26, 2015 • Lack of query-specific relevance features shallow content; • poor UX
Possum • September 1, 2016 • Tense competition in your target location
Fred • March 8, 2017 • Thin, • affiliate-heavy or ad-centered content