The Web trends & SEO practices have been dominated by famous algorithm updates, search index changes and refreshes of Google! Whenever search ranking algorithms of Google are updated, sites can do better or worse in the search results.
Panda (February 24, 2011)
Hazards: Duplicate, plagiarized or thin content; user-generated spam; keyword stuffing
Assigning a supposed “quality score” to web pages; which is then used as a ranking factor. Panda rollouts have become more frequent, so both penalties and recoveries now happen faster.
Penguin (April 24, 2012)
Hazards: Spammy or irrelevant links; links with over-optimized anchor text
The Penguin’s update works real time & down-ranks sites whose links seem manipulative. A part of Google’s core algorithm since late 2016.
Hummingbird (August 22, 2013)
Hazards: Keyword stuffing; low-quality content
The Hummingbird update makes it possible for a page to rank for a query even if it doesn’t contain the exact words the searcher entered. Keywords are still important.
Pigeon (July 24, 2014 (US); December 22, 2014 (UK, Canada, Australia))
Hazards: Poor on- and off-page SEO
Local searches were most affected by Pigeon algorithm update. Closer ties are created between the local algorithm and the core algorithm. Local results ranked by traditional SEO factors.
Mobilegeddon (April 21, 2015)
Hazards: Lack of a mobile version of the page; poor mobile usability
The Mobile Update ensures that mobile-friendly pages rank at the top of mobile searches & others are filtered out from the SERPs.