How does the Google algorithm work? Search ranking, spiders and SEO


All details of Google's algorithm are hidden behind a curtain much like this. (The slightly smug-looking stock photo model represents Google.)

The Google search algorithm is a question wrapped within an enigma hidden behind a shiny and distracting curtain.


Piecing together some idea of how the Google algorithm works is the job of SEO specialists the world over.


Typing a short query into a search engine and getting the right information back is pretty much a given these days. But if you think about it, even a simple search is actually a massively difficult task...


Because the internet is big. (For this and many other obvious observations, tune in next week.) This sheer size makes returning the most relevant information an incredible complex challenge.


Enter, stage right, search engines.


More specifically, enter search engine algorithms.


What is an algorithm?

An algorithm is a set of rules which solve a problem in a number of steps. They “show”, “describe” or “outline” – depending on how it's useful to you to mentally imagine it – how a computer will mathematically perform a finite task.


As an example, imagine you have a page in a textbook. You want your algorithm to find the line on the page with the instructions for “how to grow a magic money tree.”


You might design your algorithm to, simplistically, search every line of text and check it against that phrase until it finds the right one.


If you extend this rather strained, fringe-accurate metaphor, you get some idea of how the Google algorithm works.


How does the Google algorithm work?

The difference in scope between finding a phrase in a single page of text and in the something like 150 000 000 websites on the internet necessitates Google's search algorithm being slightly more complicated than our magic money tree example might have been.


The other change in scope is that there was only one instance of the magic money tree instructions to find in our example. On the internet, there may be thousands or even millions of instances of an answer to the question you're asking.


These are the two basic functions of the algorithm Google uses:

  1. To find and display the information that you want.

  2. To do so in order of relevance and quality.


How does Google organise the information it gathers?

Actual image of Google's filing system.

The Google algorithm likely has hundreds of different ways of organising the information it gathers. Google keeps the actual details a closely guarded secret...


But the most important ranking factors are generally agreed to be:

  • Keywords: the keywords you've chosen and where and how many times they appear on a page, such as in your page title, meta descriptions, headers and the main body of your content.

  • Links: how many links you have leading to your page, how old they are, how authoritative the linking website is and how many other sites it links to (the more it links to, the less powerful its links are thought to be).

  • Mobile search: one of the latest Google updates of 2018 doubled down on Google's mobile-first indexing system. This means that how well your website performs on mobile devices is now a key part of how well it ranks.

The two important parts of how a search engine works that we're imagining – gathering data on pages and then organising them according to these ranking factors – are accomplished through two different systems.


These are the programs most often called spiders and some kind of ranking system:


1) How do Google spiders work?

I'm not doing a mildly humorous stock image for "spiders". You're welcome.

Finding that data in the first place is the job of Google's spiders. They're also sometimes called “crawlers”.


A spider is an automated program whose job is to go through all of the pages on the internet, following all the links and build an index page for individual keywords.


When you search for something using a search engine like Google, it's the index page for search terms like the one you've typed which the engine will look at. Then it will whip up a list of results to show you.


So that's spider basics in a nutshell. It's also worth pointing out that they also likely do other things too, such as making sure that the pages they're indexing are real pages.


2) PageRank – Google's ranking system

Many people tend to think that the Google algorithm has names like “Penguin” or “Panda”. These are actually the names of Google algorithm updates.


Just for fun (though they claim it's actually to make it work better), Google updates their algorithm several hundred times a year. The smaller ones don't usually get mentioned. But the big Google updates are all named after animals.


Cute! Well, sort of.


In any case, it's these major updates which it's important to keep on top of if you want the pages on your site to rank well.


Yet these are often only really changes to the weighting of the factors which the engine uses to rank results. Google's overall system for deciding where your page will be placed on a Search Engine Results Page (SERP) is called PageRank.


(Sidenote: Somewhat unexpectedly for a system which is designed to rank pages, PageRank is apparently named after Larry Page, one of Google's founders. Not just because of its ability to rank pages.)


How the Google search engine works step by step

Here's how the algorithm basically works (at least, how it works in a way which is mentally easy to grasp):

  1. Sends out its spiders to gather data from the internet.

  2. Looks at all of the different ranking factors (such as keyword placement, number of links, ease of mobile use etc.) which the spiders have gathered and the importance the engine has been told each has via the latest update.

  3. Assigns each page a numerical “rank” for each factor.

  4. Adds up all the different ranks to create an overall page rank.

  5. Organises those pages into a list, with the highest ranking page first.

  6. Shows you that list as a Search Engine Results Page.

"Understanding how Google's algorithm works is simple" - no-one ever.

If you want a more detailed breakdown directly from the horse's mouth, you can see how search algorithms work over on the Google website.


How does the Google algorithm work for SEO?

SEO broadly includes all of the methods which you can use to signpost to Google and other search engines that your page is relevant to the topic at hand. Thus, that it's worthy of ranking first on an SERP.


Most freelance copywriters, SEO agencies and other professionals will agree that writing interesting, engaging content is your best bet for boosting your website up the search engine rankings.


This is in large part because getting those backlinks is one of the most important factors. Convincing someone to link to your site is much easier when you have content which is worthy of linking to.


You'll see your ranking rise up and fall down SERPs as you and your competitors make changes and Google spiders run around checking the links, "reading" pages and returning data so that PageRank can calculate your overall “score” anew.


Google algorithm updates in 2019 and on into the future

Having at least some knowledge of the way search engine algorithms work is very useful. Deeper knowledge of the changes major Google updates have made to its algorithm, even more so.


On the other hand, trying to “do something clever” or game the system rarely works well. Or, if it does, it's unlikely to work for long. Plus, Google is getting better at penalising sites which have been known to do this.


This doesn't mean you need to dramatically redesign your site every time Google releases as update. Stay abreast of the major changes and make sure your content is always well written, useful and easy to read and you'll be doing most of the hard work.


Remember – Google releases around 500 small updates to its algorithm every year. It's simply not possible to constantly edit your site to keep track of them all.


In fact, if you do have time, I'd love to meet you. I might need to borrow your time machine on occasion.


Want to know more about how the Google algorithm works? Need to navigate the murky waters of SEO better to boost your site rankings?


Leave a comment or fire me an email directly at benjamindmaiden@gmail.com.


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