SEOers all across the world closely follow news about Google's changes to their algorithms. It defines our job and, to a large extent, measures our success. But with literally thousands of changes, it's hard to keep track of them all.
Hubspot and Moz teamed up to assemble the following visual presentation of all these changes. As I looked over the list, it amazed me just how long ago some of these changes went into effect. For instance, who doesn't still to this day receive requests for reciprocal links in their email inbox each week. Google cracked down on this in OCTOBER of 2005!
The fact is, if you optimize your site the right way, you don't have to worry about these algorithmic changes. They only weed out the spammy competition and serve to boost your own site's rankings.
What it boils down to is: create amazing content which answers questions that visitors to your site have in an organized and natural way and you'll rise in the rankings. Try to scam Google and you'll certainly lose rankings.
Incidentally, worth noting is that Google recently changed their Page Layout algorithm. As of Feb 6 2014, pages that bury their page content too far below ad placements will be punished in the search engines. If you recently noticed a drop in rankings, check how many ads push your page content down the page.