Since its infancy, the Google Algorithm has over 200 major ranking signals that can have up to 10,000 variations or sub-signals. Over the years all kinds of updates have been rolled out to help reduce spam and increase the quality of the search results for the end user. There are 5 main updates that summarize how SEO changed in 2015.

1. RankBrainSeo Content

RankBrain is a machine-learning artificial intelligence system that is used to help process Google’s search results. It’s used as a way to interpret the search queries to find pages that might not have the exact words that were searched for. For example, if a user searches for “what foods do vegetarians eat” the results look something like this:

As you can see, the search query was pretty broad so Google served up three very possibly relevant website pages. The RankBrain system is said to be part of Google’s Hummingbird Search Algorithm. No official important signals have been identified by Google and they may not define any at all. However, if your site’s content is very relevant to the potential subject matter that the user is searching for and has a lot of relevant backlinks pointing to it, your content may be displayed as a search result.

2. Panda 4.2

Introduced in February of 2011, this update was put into place to stop websites with poor quality content from working their way into Google’s top search results. In September and May of 2014, new updates were implemented and affected approximately ten-to-twelve percent of search queries. The Panda 4.2 update affected only two-to-three percent of search queries. The most recent update is technically a refresh and not a full update; however, it’s affecting many high quality small and medium sites who do not update their content on a regular basis.

3. The Quality Update aka The Phantom 2 Update

This update was reported to have hit mircoblogs, news sites, and how-to sites the hardest. Websites such as eHow, WikiHow, and Answers.com are a few sites who seem to have been hit pretty hard by the update. The name “Phantom” was due to the lack of warning from Google. The objective of this update was to remove “thin” websites from the search results. Meaning, websites that simply list instructions without a good amount of images and videos to support it. Also affected were clickbait articles, sites with an abundance of supplementary information, pages of stacked videos, and pages difficult to navigate.

4. Mobile Update aka Mobilegeddon

This update was pre-announced giving website owners a warning that mobile rankings would differ for mobile-friendly sites starting on April 21st. The impact of this update was, in the short-term, much smaller than expected. The update was reported to have completely rolled out on April 22nd. This update did a lot for mobile user experience aside from displaying results that could be viewed properly on mobile devices. If a user is signed into their Google account on their mobile device, they will receive more relevant app results from app indexing.

According to Google, “App Indexing lets Google index apps just like websites. Deep links to your Android app appear in Google Search results, letting users get to your native mobile experience quickly, landing exactly on the right content within your app.” So, if you search for a topic in Google on a mobile device, the search results will display as both relevant website results and relevant content within the apps installed on your mobile device. For example, if you are searching for a restaurant and you have Yelp installed on your mobile device, Google will pull the result from the app and give you a link to that particular restaurant in your app.

5. February 4th Unamed, Unconfirmed Update

This update affected the SERPs in E-Commerce for heavy traffic keywords. The websites affected were mostly retailers and price comparison websites, however, the update was not limited to only these type of sites. The main signal for this update seemed to be keywords containing brand names. Brand searches were optimized along with correcting typos with the proper brand SERP.

Get ready for a 2016 full of change, too! Did we miss any of your favorite SEO changes from 2015?