We mark the dates that Google updated its algorithm so that you can can tell if big changes in your rankings fall in line with Google’s updates.
Major Algorithm Update refers to the roll-out of one or many significant algorithm changes that often fundamentally alter the way search results are indexed and ranked. The Google Page Experience Update was a major update in 2021.
Past updates Panda and Penguin are major as well, but you would have to be digging far into a domain's history to see them affecting it. Both of those hit about 10 years ago.
Google Search Quality Updates aim to down-rank or otherwise penalize domains or pages believed to be employing unfair or unintended methods to manipulate search results. These methods include questionable link practices, over-optimization, and various other types of “black hat SEO.”
Freshness Updates are regularly used by Google to keep search results relevant and up-to-date. They primarily affect search results that involve recent events or hot topics, regularly recurring events, or frequent updates.
New Feature or Enhancement Update refers to any improvements or additions to Google Search properties. These types of updates include roll-outs of and improvements to features like Local Search and Enhanced Search. It often seems experiments come and go like Google+ and Google Instant.