Google Algorithm Updates - 2013

Authorship Shake-up - December , 2013
As predicted by Matt Cutts at Pubcon Las Vegas, authorship mark-up disappeared from roughly 15% of queries over a period of about a month. The fall bottomed out around December 19th, but the numbers remain volatile and have not recovered to earlier highs.
Google's December Authorship Shake-up (Moz)

Penguin 2.1 (#5) - October, 2013
After a 4-1/2 month gap, Google launched another Penguin update. Given the 2.1 designation, this was probably a data update (primarily) and not a major change to the Penguin algorithm. The overall impact seemed to be moderate, although some webmasters reported being hit hard.
Penguin 5, With The Penguin 2.1 Spam-Filtering Algorithm, Is Now Live (SEL)
Google Penguin 2.1 Was A Big Hit (SER)

Hummingbird - August , 2013
Announced on September 26th, Google suggested that the "Hummingbird" update rolled out about a month earlier. Our best guess ties it to a MozCast spike on August 20th and many reports of flux from August 20-22. Hummingbird has been compared to Caffeine, and seems to be a core algorithm update that may power changes to semantic search and the Knowledge Graph for months to come.
FAQ: All About The New Google "Hummingbird" Algorithm (SEL)
Some Reports Of An August 21/22 Google Update (SER)

In-depth Articles - August , 2013
Google added a new type of news result called "in-depth articles", dedicated to more evergreen, long-form content. At launch, it included links to three articles, and appeared across about 3% of the searches that MozCast tracks.
In-depth articles in search results (Google)
Inside In-depth Articles: Dissecting Google's Latest Feature (Moz)

Knowledge Graph Expansion - July , 2013
Seemingly overnight, queries with Knowledge Graph (KG) entries expanded by more than half (+50.4%) across the MozCast data set, with more than a quarter of all searches showing some kind of KG entry.
The Day the Knowledge Graph Exploded (Moz)

Panda Recovery - July , 2013
Google confirmed a Panda update, but it was unclear whether this was one of the 10-day rolling updates or something new. The implication was that this was algorithmic and may have "softened" some previous Panda penalties.
Confirmed: Google Panda Update: The "Softer" Panda Algorithm (SER)

Multi-Week Update - June , 2013
Google's Matt Cutts tweeted a reply suggesting a "multi-week" algorithm update between roughly June 12th and "the week after July 4th". The nature of the update was unclear, but there was massive rankings volatility during that time period, peaking on June 27th (according to MozCast data). It appears that Google may have been testing some changes that were later rolled back.
Google's "Multi-Week" Algorithm Update (Moz)
Google's Matt Cutts: Multi-Week Update Rolling Out (SER)

"Payday Loan" Update - June, 2013
Google announced a targeted algorithm update to take on niches with notoriously spammy results, specifically mentioning payday loans and porn. The update was announced on June 11th, but Matt Cutts suggested it would roll out over a 1-2 month period.
Google Payday Loan Algorithm: Google Search Algorithm Update To Target Spammy Queries (SEL)
Google Spam Algorithm For Spammy Queries: Pay Day Loans+ (SER)

Panda Dance - June , 2013
While not an actual Panda update, Matt Cutts made an important clarification at SMX Advanced, suggesting that Panda was still updating monthly, but each update rolled out over about 10 days. This was not the "everflux" many people had expected after Panda #25.
Google’s Panda Dance: Matt Cutts Confirms Panda Rolls Out Monthly Over 10 Of 30 Days (SEL)

Penguin 2.0 (#4) - May , 2013
After months of speculation bordering on hype, the 4th Penguin update (dubbed "2.0" by Google) arrived with only moderate impact. The exact nature of the changes were unclear, but some evidence suggested that Penguin 2.0 was more finely targeted to the page level.
Penguin 2.0/4 - Were You Jarred and/or Jolted? (SEOmoz)

Domain Crowding  - May, 2013
Google released an update to control domain crowding/diversity deep in the SERPs (pages 2+). The timing was unclear, but it seemed to roll out just prior to Penguin 2.0 in the US and possibly the same day internationally.
Google Domain Crowding Update: May 2013 (High Position)
Google Domain Clustering Update (Justin Briggs)

"Phantom" - May , 2013
In the period around May 9th, there were many reports of an algorithm update (also verified by high MozCast activity). The exact nature of this update was unknown, but many sites reported significant traffic loss.
A Google Update Is Happening (Google: Nothing To Announce Now) (SER)
SEO Findings From Google’s Phantom Update (GSQi)

Panda #25 - March , 2013
Matt Cutts pre-announced a Panda update at SMX West, and suggested it would be the last update before Panda was integrated into the core algorithm. The exact date was unconfirmed, but MozCast data suggests 3/13-3/14.
Google Panda Update 25 Seems To Have Hit (SEL)

Panda #24  - January , 2013
Google announced its first official update of 2013, claiming 1.2% of queries affected. This did not seem related to talk of an update around 1/17-18 (which Google did not confirm).
Google Announces 24th Panda Refresh; Not Related To January 17th (SER)
Google Panda Update Version #24; 1.2% Of Search Queries Impacted (SEL)

Click here For Google Algorithm Change History 2014

Google Webmaster Guidelines

Best practices to help Google find, crawl, and index your site

Following these guidelines will help Google find, index, and rank your site. Even if you choose not to implement any of these suggestions, we strongly encourage you to pay very close attention to the "Quality Guidelines," which outline some of the illicit practices that may lead to a site being removed entirely from the Google index or otherwise impacted by an algorithmic or manual spam action. If a site has been affected by a spam action, it may no longer show up in results on Google.com or on any of Google's partner sites. 

•    Design and content guidelines

•    Technical guidelines

•    Quality guidelines
 

When your site is ready: 

•    Submit it to Google at http://www.google.com/submityourcontent/.

•    Submit a Sitemap using Google Webmaster Tools. Google uses your Sitemap to learn about the structure of your site and to increase our coverage of your WebPages.

•    Submit a Sitemap using Google Webmaster Tools. Google uses your Sitemap to learn about the structure of your site and to increase our coverage of your WebPages.

•    Make sure all the sites that should know about your pages are aware your site is online.

Design and content guidelines

•    Make a site with a clear hierarchy and text links. Every page should be reachable from at least one static text link.

•    Offer a site map to your users with links that point to the important parts of your site. If the site map has an extremely large number of links, you may want to break the site map into multiple pages.

•    Keep the links on a given page to a reasonable number.

•    Create a useful, information-rich site, and write pages that clearly and accurately describe your content.

•    Try to use text instead of images to display important names, content, or links. The Google crawler doesn't recognize text contained in images. If you must use images for textual content, consider using the "ALT" attribute to include a few words of descriptive text.

•    Make sure that your <title> elements and ALT attributes are descriptive and accurate.

•    Check for broken links and correct HTML.

•    If you decide to use dynamic pages (i.e., the URL contains a "?" character), be aware that not every search engine spider crawls dynamic pages as well as static pages. It helps to keep the parameters short and the number of them few.

•    Review our recommended best practices for images, video and rich snippets.

Technical guidelines

•    Use a text browser such as Lynx to examine your site, because most search engine spiders see your site much as Lynx would. If fancy features such as JavaScript, cookies, session IDs, frames, DHTML, or Flash keep you from seeing your entire site in a text browser, then search engine spiders may have trouble crawling your site.

•    Allow search bots to crawl your sites without session IDs or arguments that track their path through the site. These techniques are useful for tracking individual user behavior, but the access pattern of bots is entirely different. Using these techniques may result in incomplete indexing of your site, as bots may not be able to eliminate URLs that look different but actually point to the same page.

•    Make sure your web server supports the If-Modified-Since HTTP header. This feature allows your web server to tell Google whether your content has changed since we last crawled your site. Supporting this feature saves you bandwidth and overhead.

•    Make use of the robots.txt file on your web server. This file tells crawlers which directories can or cannot be crawled. Make sure it's current for your site so that you don't accidentally block the Googlebot crawler. Visithttp://code.google.com/web/controlcrawlindex/docs/faq.html to learn how to instruct robots when they visit your site. You can test your robots.txt file to make sure you're using it correctly with the robots.txt analysis tool available in Google Webmaster Tools.

•    Make reasonable efforts to ensure that advertisements do not affect search engine rankings. For example, Google's AdSense ads and DoubleClick links are blocked from being crawled by a robots.txt file.

•    If your company buys a content management system, make sure that the system creates pages and links that search engines can crawl.

•    Use robots.txt to prevent crawling of search results pages or other auto-generated pages that don't add much value for users coming from search engines.

•    Test your site to make sure that it appears correctly in different browsers.

•    Monitor your site's performance and optimize load times. Google's goal is to provide users with the most relevant results and a great user experience. Fast sites increase user satisfaction and improve the overall quality of the web (especially for those users with slow Internet connections), and we hope that as webmasters improve their sites, the overall speed of the web will improve.

Google strongly recommends that all webmasters regularly monitor site performance using Page Speed, YSlow,WebPagetest, or other tools. For more information, tools, and resources, see Let's Make The Web Faster. In addition, the Site Performance tool in Webmaster Tools shows the speed of your website as experienced by users around the world.