May 14

How Search Engines Work and Why You Need to Know This

Online marketing


You know what you need to do for SEO, but you wonder why you have to perform all these tasks. So we decided to explain in detail how search engines work. After you read this article, you will know how Google and other search engines look for results and how they decide which ones to display.

We believe that this is a very useful lesson to anyone, especially business owners and marketers that are just starting out in their SEO work. Some of the tasks appear difficult and time consuming and you may wonder if they are absolutely necessary. Once you know how search engines work, you can give yourself the answer.

Let’s Start with the Basics: What Do Search Engines Do?

Search engines are basically computerised answer machines. They discover content all over the internet, understand what it is about and organise it in their own specific libraries. In this way, they can display the right results to search queries.

However, these search engines are not all-knowing and all-powerful entities. In order to discover a site, they need to have access to it. We will cover this aspect in more detail later on in this article. For now, you need to know exactly what search engines can or cannot do.

How Search Engines Work in Discovering and Organising Internet Content

So, how do search engines discover websites? And how do they organise the content to retrieve it in such a short time for each search query?

All search engines – Google, Bing, Yahoo, Baidu and others – work in the same way, technically speaking. They do three things:

  1. they crawl websites, that is, they go through website codes and content
  2. they index website, that is, they introduce all websites they crawl in a special register
  3. they rank websites,, that is, they give scores for the best websites on a specific topic.

The fact that Google is the most popular search engine is not a surprise – its developers created the most powerful artificial intelligence machine for scanning the internet for fresh content and matching it not just with keywords, but with the user’s intent. In its constant changes to its ranking algorithm, Google is trying to weed out low quality websites, which attempt to hijack honest SEO strategies.

What Exactly Is Crawling?

How do search engines crawl websites? Is there a team of people actually looking at websites? Of course not! It would be beyond the time and effort capacities of any team to constantly look at new content, be it new websites, new pages added to sites or new text added to existing page content.

Instead, search engines send out many robots (called spiders or crawlers). They are trained using machine learning to search for content all over the internet. The crawlers start by browsing the first pages they discover in a website and continue browsing by following links pointing to and from it.

How Search Engines Work when Indexing and Ranking Pages

Now that you know the basics of what search engines do, it is time to show how they decide on the websites to display for search queries. First of all, a website must be indexed in order to show up in search results.

This is how search engines work: they identify the topic of a website through its content and keywords. Next, they record the website in their register (the index) under that specific topic – very much like books in a library organised as: fiction, children’s book, science, classic literature, etc.

Next, within this index, the search engine will compare websites on the same topic and decide which ones are more trustworthy and reliable than others. This action is called ranking. The ranking algorithm constantly changes adding new relevant factors. For example, in the last 5-6 years, mobile friendliness has become one of the most important ranking factors for Google.

You Can Control How Search Engines Work on Your Website

The good news is that you are not absolutely powerless and passive in the way search engines crawl and index your website. You can actually tell the Google spiders which pages to crawl within your site and which one to ignore.

You may have old landing pages that you want to reactivate at a later date. You may have pages with thin content, which may pull down the rank of your site, but which may be useful for some visitors. That’s alright, you do not have to delete them.

Instead, you need to exclude them from crawling in the “robots.txt” file. This is a small-sized file that any website should contain. When the Google spiders find it, they will crawl it first and follow its instructions. You can include indications concerning the order in which they should crawl your web pages, and which ones to leave out.

Why It Matters to You How Search Engines Work

So, why did we give you the technical explanations above? We want to help you understand why search engine optimisation is important and why you need to perform all the regular tasks, such as fixing code errors, adding fresh content, optimising your website for fast loading and mobile browsing.

And there is more. Knowing how search engine works helps you understand why your site is not indexed and how to fix potential errors.

The First Thing to Do: See How Many Web Pages Google Indexes

How do you know how many pages in your site are indexed by Google and will, theoretically, show up in search results? To do that, go to Google search and type in:

Attention, do not add blank spaces to the formula above. The result to this special query will be the list of all the pages in your website that Google has indexed.

Why Some Pages May Not Be Indexed

Leaving aside the pages that you excluded from indexing in the robots.txt file, here are some reasons why Google did not index your pages:

1. Brand New Website

Looking at how search engines work, you understand that they cover the entire internet searching for content. Thus, they cannot discover each new site instantly. It may take weeks until they reach yours, so be patient.

2. Your Navigation System Confuses Crawlers

An overly complicated and confusing site structure may prevent spiders from getting to every page in your site. This is something you must fix. Just think: if computerised robots cannot understand your website, what chances do your potential clients have?

3. You Unwittingly Added Code that Blocks the Crawlers

In some cases, your website may contain a piece of code called crawler directives. Its role is to block search engine spiders. It is a sort of “Do Not Enter” for the Googlebot. You need to identify it and remove it.

4. The Content Is Accessible to Members Who Log In

Premium content, available to your website members who log in, cannot be accessed by Google. This is not how search engines work – they do not sneak behind password protected gateways.

5. You Use Text in Photos on Your Web Pages

Big motivational photos with text over an image look great on the social media. However, they are absolutely useless for search engines, because they cannot read it. In fact, they do not interpret it as content at all.

6. Your Website Received a Penalty

Yes, this is how search engines work – when you try to break their rules, they penalise your website. After all, they do you a service, for free: if you are a good match for a user’s intent, they serve your website among its search results.

If you do not like these rules, you have the option to pay for CPC promoted links. Google will display them with priority, but you will have to pay for each click you get. However, with patience and good faith, you can align your website to the requirements of search engines and rank organically for searches. Good luck!

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