Each year, Google changes its search algorithm up to 500-600 times. While most of these changes are minor, every few months Google rolls out a "major" algorithmic update that affect search results in significant ways.
Outrider offers a inforgraphic timeline of Google Algorithm Changes to help SEO's gather an understanding of Google's thinking and strategies for their search engine.
Outrider also offers a full list of resources they used to gather this information -> Google Algorithm Resources.
Also, SEOMoz offers a full list of Google's algorithm changes through time.
For search marketers, knowing the dates of these Google updates can help explain changes in rankings and organic website traffic. You may already know that Larry Page and Sergey Brin named "Google" by adapting the word googol - the number one followed by one hundred zeros. This encapsulates the scope of Google's mission: To provide large quantities of information and make it universally accessible and useful.
But why Chrome, Panda, or Buffy? Below, we've listed the major algorithmic changes that made the biggest impacts on search and the most notable and peculiar names that Google has given their algorithm updates over the years:
Google Toolbar - December 2000: Google launched their browser toolbar, and with it, Toolbar PageRank (TBPR). As soon as webmasters started watching TBPR, the Google Dance began.
2002: Boston: Announced at the SES Boston, this was the first named update, before "Boston" there was a major shuffle in the Fall of 2002. The details are unclear, but this appeared to be more than the monthly "Google Dance" and "PageRank" update. These updates would majorly shake up the search engine results page (SERP) for 3-5 days and occurred approximately 10 times per year. Fast-forward to today, updates occur between 500-600 times a year!
Cassandra - April 2003: Google cracked down on some basic link-quality issues, such as massive linking from co-owned domains. Cassandra also came down hard on hidden text and hidden links.
Cassandra, Dominic, Esmeralda, Fritz were also named by the folks over at WMW.
The members decided that they wanted to name the updates similarly to how hurricane names are selected: in alphabetical order, one month male, one month female. Since the previous month's update was Boston, they went with a female name and voted on Cassandra because "we just liked it." See below why Brett Tabke, founder and owner of WMW and the PubCon conference, finalized the name.
"Dominic" was actually named after a pizza place in Boston that was frequented by PubCon attendees. The exact nature of Dominic was unclear. Google bots "Freshbot" and "Deepcrawler" scoured the web, and many sites reported bounces. The way Google counted or reported backlinks seemed to change dramatically
"Esmeralda" marked the end of the monthly "Google Dance" and the beginning of Everflux. Esmerelda probably heralded some major infrastructure changes at Google.
With "Fritz" the monthly "Google Dance" finally came to an end. Instead of completely overhauling the index on a roughly monthly basis, Google switched to an incremental approach. The index was now changing daily.
Florida - November 2003: This was the update that put updates (and probably the SEO industry) on the map. Many sites lost ranking, and business owners were furious. Florida sounded the death knell for low-value late 90s SEO tactics, like keyword stuffing, and made the game a whole lot more interesting.
There were several theories floating regarding the origins of the name "Florida" for this 2003 update. Some speculated the name came from the series of hurricanes that hit Florida.
However, like Boston, Tabke called it Florida because there was an upcoming WMW conference in Orlando.
Bourbon - May 2005: "GoogleGuy" (likely Matt Cutts) announced that Google was rolling out "something like 3.5 changes in search quality." No one was sure what 0.5 of a change was, but Webmaster World members speculated that Bourbon changed how duplicate content and non-canonical (www vs. non-www) URLs were treated.
Tabke was also the man behind the name "Bourbon" and strategically chose it to align with the WMW New Orleans conference.
Big Daddy - December 2005: Technically, Big Daddy was an infrastructure update (like the more recent "Caffeine"), and it rolled out over a few months, wrapping up in March of 2006. Big Daddy changed the way Google handled URL canonicalization, redirects (301/302) and other technical issues.
Big Daddy had Big repercussions on notorious link exchangers, link buyers and sellers. Big D was a new data center with major software upgrades implemented that affected how the algorithm crawled and indexed sites. Site pages containing suspicious links were no longer getting indexed in the new data center.
The name for the update actually came a year after it was first rolled out. It was GoogleGuy, Matt Cutts' first chance to christen an update name.
Cutts approved "Big Daddy" when at PubCon 2006 one of the webmasters suggested "Big Daddy" as the name for new data center.
Buffy - June 2007: In honor of Vanessa Fox leaving Google, the "Buffy" update was christened. No one was quite sure what happened, and Matt Cutts suggested that Buffy was just an accumulation of smaller changes. Named after the notorious link spam slayer?
Vince - February 2009: Matt Cutts called VInce a "minor change", but others felt it had profound, long-term implications. The update focused on promoting "authority" and "trust" throughout the SERP.
Google named the "Vince" update after one of their engineers (Vince) who developed and executed the project.
Caffeine - June 2010: In 2009, a preview of Caffeine was released, and after months of testing, Google rolled out the Caffeine. The goal was to drastically change the search indexing infrastructure. Caffeine not only boosted Google's raw speed, but integrated crawling and indexation much more tightly, resulting in (according to Google) a 50% fresher index.
Google called it "whole new web indexing system."
Panda/Farmer - February 23, 2011: A major algorithm update hit sites hard, affecting up to 12% of search results (a number that came directly from Google). Panda seemed to crack down on thin content, content farms, sites with high ad-to-content ratios, and a number of other quality issues.
Panda rolled out over at least a couple of months, hitting Europe in April 2011.
Like Vince, Panda was named after one of the key Google engineers who worked on the update and made it possible, Navneet Panda. Singhal and Cutts revealed that they used the code name "Panda" to refer to the update internally.
- Panda 2.0 - April 11, 2011: Google rolled out the Panda update to all English queries worldwide (not limited to English-speaking countries). New signals were also integrated, including data about sites users blocked via the SERPs directly or the Chrome browser.
- Panda 2.1 - May 9, 2011: Initially dubbed "Panda 3.0", Google appeared to roll out yet another round of changes. These changes weren't discussed in detail by Google and seemed to be relatively minor.
- Panda 2.2 - June 21, 2011: Google continued to update Panda-impacted sites and data, and version 2.2 was officially acknowledged. Panda updates occurred separately from the main index and not in real-time, reminiscent of early Google Dance updates.
- Panda 2.3 - July 23, 2011: It was unclear whether new factors were introduced, or this was simply an update to the Panda data and ranking factors.
- Panda Goes Global (2.4) - August 12, 2011: Google rolled Panda out internationally, both for English-language queries globally and non-English queries except for Chinese, Japanese, and Korean. Google reported that this impacted 6-9% of queries in affected countries.
- Panda 2.5 - September 28, 2011: Google rolled out another Panda update. Specific details of what changed were unclear, but some sites reported large-scale losses.
- Panda "Flux" - October 5, 2011: Cutts tweeted: "expect some Panda-related flux in the next few weeks" and gave a figure of "~2%". Other minor Panda updates occurred on 10/3, 10/13, and 11/18.
- Panda 3.1 - November 18, 2011: After Panda 2.5, Google entered a period of "Panda Flux" where updates started to happen more frequently and were relatively minor. Some industry analysts called the 11/18 update 3.1, even though there was no official 3.0. For the purposes of this history, we will discontinue numbering Panda updates except for very high-impact changes.
- Panda 3.2 - January 18, 2012: Google confirmed a Panda data update, although suggested that the algorithm hadn't changed. It was unclear how this fit into the "Panda Flux" scheme of more frequent data updates.
- Panda 3.3 - February 27, 2012: Google rolled out another post-"flux" Panda update, which appeared to be relatively minor. This came just 3 days after the 1-year anniversary of Panda, an unprecedented lifespan for a named update.
- Panda 3.4 is 'Rolling Out Now': Google has announced the latest in its ongoing updates to the Panda algorithm that targets low-quality websites. As the tweet below says, Google estimates that about 1.6 percent of queries are affected by this "Panda refresh."
Panda refresh rolling out now. Only ~1.6% of queries noticeably affected. Background on Panda: goo.gl/mTKCH-- A Googler (@google) March 23, 2012
For more background on Google's Panda updates, see the infographic "Panda: One Year Later infographic" embedded below: