https://yoast.com/google-algorithm-updates/
A brief history of Google’s algorithm updates
These days, the way we do SEO is somewhat different from how things were done ca. 10 years ago. There’s one important reason for that: search engines have been continuously improving their algorithms to give searchers the best possible results. Over the last decade, Google, as the leading search engine, introduced several major updates, and each of them has had a major impact on best practices for SEO. Here’s a — by no means exhaustive — list of Google’s important algorithm updates so far, as well as some of their implications for search and SEO.
2011 – Panda
Obviously, Google was around long before 2011. We’re starting with the Panda update because it was the first major update in the ‘modern SEO’ era. Google’s Panda update tried to deal with websites that were purely created to rank in the search engines, and mostly focused on on-page factors. In other words, it determined whether a website genuinely offered information about the search term visitors used.
Two types of sites were hit especially hard by the Panda update:
Affiliate sites (sites which mainly exist to link to other pages).
Sites with very thin content.
Google periodically re-ran the Panda algorithm after its first release, and included it in the core algorithm in 2016. The Panda update has permanently affected how we do SEO, as site owners could no longer get away with building a site full of low-quality pages.
2012 – Venice
Venice was a noteworthy update, as it showed that Google understood that searchers are sometimes looking for results that are local to them. After Venice, Google’s search results included pages based on the location you set, or your IP address.
2012 – Penguin
Google’s Penguin update looked at the links websites got from other sites. It analyzed whether backlinks to a site were genuine, or if they’d been bought to trick the search engines. In the past, lots of people paid for links as a shortcut to boosting their rankings. Google’s Penguin update tried to discourage buying, exchanging or otherwise artificially creating links. If it found artificial links, Google assigned a negative value to the site concerned, rather than the positive link value it would have previously received. The Penguin update ran several times since it first appeared and Google added it to the core algorithm in 2016.
As you can imagine, websites with a lot of artificial links were hit hard by this update. They disappeared from the search results, as the low-quality links suddenly had a negative, rather than positive impact on their rankings. Penguin has permanently changed link building: it no longer suffices to get low-effort, paid backlinks. Instead, you have to work on building a successful link building strategy to get relevant links from valued sources.