Google has a long history of famous algorithm updates, search index changes and refreshes.
Below are links to some of the most important resources for search marketers:
Google Hummingbird
Google Mobile Friendly Update
Google Panda Update
Google Penguin Update
Google Pigeon Update
Google Payday Update
Google Pirate Update
Google EMD (Exact Match Domain) Update
Google Top Heavy Update
Each year, Google changes its search algorithm around 500–600 times. While most of these changes are minor, Google occasionally rolls out a "major" algorithmic update (such as Google Panda and Google Penguin) that affects search results in significant ways.