The Google algorithm — that’s the subject of this lesson. But what exactly is the Google algorithm? How does it work, how often is it updated, and which of its updates matter most? How did the changes that followed the June 2019 Core Update and the others show up in the search results, and therefore in the way Search Engine Optimization (SEO) itself is done? There’s plenty to get through.
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If this lesson interests you, it’s probably because you want to understand exactly how the Google algorithm works, so you can improve your SEO strategy and reach your business goals.
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What is the Google algorithm?
The Google algorithm is the heart of the complex system that lets the Mountain View company’s search engine process, in an instant, the countless pieces of information in its index and return to users the most useful, most relevant results for a given search term (or keyword).
But what exactly is an algorithm?
In general, an algorithm is defined as a set of rules that solve a problem in a finite number of elementary steps (operations or instructions) that cannot be broken down further.
Source: Wikipedia
In computing, those operations or instructions are translated into machine language (a program) that a computer can then run to carry out a task or solve a specific problem.
But how exactly does Google’s algorithm decide which results to show, and in what order?
Read on — we’ll find out in the sections below!
How does the Google algorithm work?
How does Google’s search algorithm work? Strictly we should talk about Google algorithms, plural: Big G uses a main algorithm (Hummingbird) in combination with other algorithms and a great many ranking factors, or signals, to return in its search engine results pages (SERPs) an ordered list of information useful and relevant to the user.
Google itself gives us pointers on how search algorithms work (more here) and how they are used to return the information a user asked for.
Here are the stages.
Analysing the words
The first step involves analysing the meaning of the words used in the search query and building language models, in order to work out exactly what the user is looking for.
Matching the search
The algorithms then look for the search terms (not repetitions of them) in the index in order to return appropriate results.
Ranking useful pages
Somewhere between myth and reality, the search engine is held to weigh over 200 factors when ranking, with some 10,000 variations of “sub-signals” (more here).
Various pieces of research, such as those by SEMrush (Ranking Factors 2.0) and Brian Dean (Backlinko), have tried to describe and categorise them, infographics included (here’s one). The ones named in 2016 by Andrey Lipattsev, Google’s Search Quality Senior Strategist, are essentially three: links, content and RankBrain.
Image from hubspot.com
Among those signals are a page’s relevance and authority. The first comes from the Google algorithm’s assessment of how well the content reflects the user’s search intent — historically tied closely to keyword density. The second is measured by a numerical value (1 to 10) assigned by the PageRank algorithm, part of Hummingbird, according to the quality of the site’s link profile.
Image from andreaminini.com
Both are treated as signals and processed by the algorithm for the final assessment. It’s precisely the inspired idea of putting links between websites into the search algorithm as a variable for calculating relevance that made Google the most used search engine in the world.
Returning the best results
Before publishing, Google weighs how all the information it has gathered fits together, so as to give results that match users’ search intent as closely as possible.
Taking context into account
By drawing on information such as location, settings and past search history, Google’s algorithm can serve personalised results. If you search for “pizza” at 9 in the morning you’re probably after the recipe; run the same search at 8 in the evening and you may well be looking for a pizzeria.
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The Google algorithm: updates and refreshes
As we’ve seen, Google’s main algorithm is called Hummingbird, and it’s updated hundreds of times a year: sometimes the changes are minor, sometimes significant. The significant ones especially can move where content ranks in the SERP.
Working out when they happen and what they consist of helps marketers sharpen their SEO strategy and make their SEO campaigns more effective.
Below, in chronological order, are the main updates over the years, going back almost to 1998, the year Google was founded.
June Core Update
The 2019 Google algorithm update shipped on 3 June. Danny Sullivan confirmed it and gave it its name in reply to Barry Schwartz in a Twitter exchange on 2 June, later gathered into a post (here it is).
The fact that a core update was pre-announced for the first time tells us a great deal about how important it was. The aim is to keep improving search results proactively.
It’s still early, but compared with the 2018 Google algorithm, research by Searchmetrics (here) already found, in a single week, a 25% rise in YouTube video carousels and a fall for low-quality sites out of step with the E-A-T (Expertise, Authoritativeness, Trust) guidelines, and for small sites.
Deindexing bug
This brought an end to the de-indexing episode Google started on 4 April, which caused so much upheaval among SEOs. According to research by Moz, 4% of indexed pages were affected — and, remarkably, the cause wasn’t an algorithm update at all but a bug the Mountain View company itself hadn’t known about.
March Core Update
Announced on 12 March via Twitter by Danny Sullivan, this update (initially christened Florida 2) is a “broad core” one — it affects URLs indiscriminately. The improvements concern how the Google algorithm judges content relevance against a given keyword. The aim is to give the user the most useful resource possible.
Image from twitter.com
Medic Core Update
Released on 1 August, this update was also a “broad core” one. The hardest hit, with SERP drops of 25–30%, were international and “medical” sites, though not only those. Working on the brand and creating quality content in line with Google’s guidelines were again named by Danny Sullivan as the actions to take in order to climb back up the SERP.
Image from twitter.com
Mobile Speed Update
Released on 9 July, this update saw Google penalize sites with slow load times, chiefly on mobile devices. Speed thus became a ranking factor. But which pages does Google’s algorithm consider fast? The factors weren’t specified, but it was made clear that only three tools are accredited to assess a page’s performance: PageSpeed Insights, Lighthouse and the Chrome User Experience Report.
Unnamed Core Update
Released by Google on 16 April after an announcement on Twitter, this update focuses on content relevance. Content that better answers users’ search intent and informational needs ranks better in the SERPs — as John Mueller himself said during a hangout. Marketers therefore have to work harder to understand who their audience is and how it interacts with their content.
Image from twitter.com
Mobile-First Index Roll-out
On 26 March, announced in a post on the Webmaster Central blog, Google released this core update. It matters a great deal, because from that moment the Mountain View search engine’s primary index was no longer desktop but mobile.
Zero-result SERP Test
On 20 March Danny Sullivan announced that Google had started, and then stopped, a test in which for certain kinds of answer (calculators, unit conversions, data queries) the SERP returned zero results. Even though it was pulled, the test is an example of a possible future in which organic results as we know them are replaced by an information card with a “show all results” button.
Image from moz.com
Brackets Core Update
Released on 9 March, this “broad core” update focuses on content quality and aims to “benefit pages that were previously under-rewarded” but are relevant to a search query. Once again, Big G names creating quality content as the only route to climbing the SERP.
Image from twitter.com
Maccabees, or the pre-holiday update
Released on 15 December, this update’s effects showed up in the SERPs, mainly on mobile, on sites without schema markup and on doorway pages. Analysis with the SEMrush Sensor tool showed general SERP volatility across different sectors and in six different countries.
Image from searchengineland.com
Snippet Length Increase
Released on 30 November after years of testing, this update increased snippet length in the search results. The meta description famously went from 155 to 300 characters, giving more room to catch users’ attention and win clicks. Just as famously, the decision was reversed a few months later.
Hawk local algorithm update
Released on 22 August, this update affects local searches only. Specifically, it changes how Google filters results through an improved proximity filter. Unlike with the previous update (Possum, September 2016), one of two businesses in the same building no longer risks being filtered out of the local results.
Unnamed Update
Released on 17 May, this update appeared from the outset to hit sites making heavy use of deceptive advertising tactics.
Fred update
Released on 8 March, this update — never confirmed by Google — appears to focus more on link quality than on content quality. The name “Fred” came from Gary Illyes, who joked that from then on every unnamed update would be called Fred.
Image from twitter.com
Chrome security warnings
Released on 7 March, this Chrome update aims to provide greater security in case an attacker tries to take control.
Intrusive Interstitial Penalty
This “broad core” update was released on 10 January and targeted sites using intrusive pop-ups and banners that hurt the mobile user experience. The previous update (Penguin 4.0 announcement, 23 August 2016) had had little effect on sites running aggressive advertising.
Penguin 4.0 announcement
Released on 23 September after an announcement from Gary Illyes on Twitter, this new version of Google Penguin was implemented and fully integrated into Hummingbird. The goal was to answer queries with more relevant, higher-quality content and to punish sites using black hat SEO tactics such as keyword stuffing.
Mobile friendly update #2
Released on 12 May, this update gives a lift to the rankings of mobile-friendly sites and pages. A year on from the previous one, it makes official that mobile friendliness is a ranking factor.
RankBrain
With this update, confirmed on 26 October, the Google algorithm integrated artificial intelligence to process search results and give users the most relevant ones. That same year the Mountain View company named RankBrain one of its three main ranking factors.
Panda 4.2
This 28th refresh rolled out gradually from 22 July, ten months after the previous one (Panda 4.1, 25 September 2014). Those hit were mainly English-language sites and, in keeping with the other Panda refreshes, sites and pages with thin or duplicate content.
Mobile update, AKA “Mobilegeddon”
Released on 21 April but announced by Big G the following day, this update focuses on favouring the organic rankings of sites and pages that display well and give a proper UX on mobile devices. The algorithm examines design and user interface to judge how sites handle smaller screens.
Local Pigeon Expands update (UK, CA & AU)
Pigeon shipped in the US on 24 July and was extended on 22 December to Canada, the UK and Australia only. The goal of this Google algorithm update was to deliver local results that were as useful, relevant and accurate as possible.
Penguin Everflux
Like Panda, Penguin became everflux, updated continuously so as to judge site quality faster. From 10 December, a penalized site could recover from a penalty by removing links manually or disavowing them.
Pirate 2.0
Confirmed by Google on 21 October, almost two years after the original DMCA/“Pirate” filter (10 August 2012), this refresh targets piracy in software and digital media, hitting sites with multiple copyright infringement reports.
Penguin 3.0
The sixth Penguin release, global (affecting sites in different languages and regions), dated 17 October. Unlike before everflux, a penalized site no longer had to wait for the next release to see whether its changes had worked. The algorithm hits sites with a poor backlink profile and, conversely, promotes those that have “cleaned up” their link profile.
HTTPS/SSL update
Released on 6 August, this update saw Big G announce that sites choosing to use SSL certificates, and so to be more secure, would get a “slight boost” up the SERP.
Panda 4.0 (#26)
Released on 19 May, this was both a broad core update and a data refresh. Matt Cutts announced it on Twitter the following day. According to the official figures, 7.5% of English-language queries were affected, along with queries in other languages.
Penguin 2.1
The fifth Penguin release, dated 4 October. With this update the Google algorithm set out to fight web spam. Its impact was moderate, as announced on Twitter by Matt Cutts, head of Google’s web spam team, and put at 1% of all searches.
Hummingbird
Released on 20 August but confirmed by Big G on 26 September, this significant “broad core” update affected semantic search and the knowledge graph. The “hummingbird” is fast and accurate at assessing queries, and gives real weight to natural language, context and meaning beyond the keyword itself.
Panda Recovery
Confirmed on 18 July, this update softened some of Google Panda’s harsher effects, which had penalized various sites, and helped those sites recover positions in the SERPs.
Exact-Match Domain (EMD) Update
Released on 27 September, this update changed how exact match domains (EMDs) are handled. Big G wanted to stop low-quality sites ranking well simply because their domain contained words that happen to be heavily searched keywords.
Penguin
This broad core update was released on 24 April to reward quality sites in the SERP, exclude those using black hat practices such as link manipulation or keyword stuffing, and “adjust” certain spam factors.
Venice
Confirmed on 27 February, this update had a broad effect on local searches and made Google Places integrations appear far more often in the SERP.
Google+
Confirmed on 28 June, this release was Big G’s answer to Facebook on social content sharing. It worked at first — 10 million users within two weeks of launch — but as we know, Google+ is no longer available.
Schema.org
Confirmed by Big G, Yahoo and Microsoft, schema.org markup (structured data) launched on 2 June with support from the major search engines. Not every markup produces rich snippets or improves search results, though.
Panda 2.0 (#2)
Released on 11 April, this refresh affected English-language queries worldwide. Google uses various signals to determine which results are relevant; new ones were now brought in, including data from sites users had blocked directly through a Chrome extension.
The +1 button
To answer competition from the major social networks, Big G introduced the +1 button on 30 March. Clicking it let a user influence search results within their own community.
Caffeine (rollout)
Released on 1 June but announced by Big G the year before, Caffeine was a new web indexing system. The Google algorithm now analyses the web continuously so as to serve users fresh, current content. According to Google’s figures, 35% of searches were affected.
MayDay
Released on 1 May, this update had a significant effect on the organic traffic of sites making heavy use of long-tail keywords, ecommerce sites among them — as Matt Cutts himself confirmed. The goal was to raise the quality of the content served in the search results.
Google Places
On 1 April Big G officially launched Google Places (now Google My Business), which was in fact a re-branded Local Business Center. Users could now connect more easily with business information, including video, coupons and special offers. New features arrived too, such as service areas and new local advertising options.
Real-time search
Confirmed on 1 December, with this Google algorithm update Twitter feeds, Google News, social media and other sources were integrated into a real-time feed on certain SERPs. It could be stopped with the “Pause” link at the top right.
Image from searchengineland.com
Rel-canonical tag
Released on 1 February and announced jointly by Google, Yahoo and Microsoft, this update let webmasters tell search engines which of two or more versions of a piece of content to show, without affecting how users see it.
Google Suggest
Released on 1 August after almost four years of testing, this update showed users running a search a short list of keywords related to their search term at the bottom of the page.
Universal Search
Confirmed on 1 May, this update ended the old SERP made up of a list of 10 results. In the new SERP, links are integrated with news, video, local results and images in various formats, placed vertically as well.
Big Daddy
Confirmed on 1 December, this core update to the Google algorithm brought a major change to Big G’s infrastructure and to SERP quality. In particular, Big Daddy changed how Google handles URL canonicalization, redirects and other technical issues.
Google Local / Google Maps
Confirmed on 1 October, this refresh followed March’s launch of the Local Business Center, into which map data was integrated — with consequences for local SEO.
XML sitemaps
Confirmed on 1 June, this update let webmasters submit XML sitemaps through Webmaster Tools (now Google Search Console), bypassing traditional HTML sitemaps and giving SEOs a small measure of influence over crawling and indexing.
Nofollow
Confirmed on 1 January, Big G, Yahoo and Microsoft jointly introduced the nofollow tag to fight spam and control backlink quality.
Brandy
Confirmed on 1 February, this update brought several changes from Google: a larger index, greater attention to anchor text relevance and to Latent Semantic Indexing (LSI). The last of these in particular improved its grasp of synonyms, and with it the depth of keyword analysis.
Florida
Confirmed on 1 November, Florida was the first major Google algorithm update, and the first to shake the SERPs significantly in the run-up to Christmas. Florida destroyed the way SEO was done at the time, opening the door to a new era for Search Engine Optimization.
Conclusion
In this lesson of your favourite SEO Academy we’ve covered the Google algorithm. You now have what you need to understand how a search algorithm works, along with a short summary of the updates Google has been through, from the beginning to the present day.
Search engines are constantly trying to improve how they serve users relevant, accurate results for a given query. Machine learning, artificial intelligence, semantic SEO — these are just some of the recent arrivals that affect where content ranks, and therefore how SEO is done, and we’ll keep covering where they lead in the lessons ahead.
Stay tuned and keep following us — in the next lessons of the SEO Academy we’ll get into plenty more interesting territory…
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