How Search Engines Work

How Search Engines Work

Before I talk about how search engines work, let me ask you a question.

What actually is a search engine and why do you think it is important to understand how search engines work?

A search engine is a software system that helps users find the exact information they are looking for online as quickly as possible. They search an index of the world wide web for keywords and display the results in order of their relevance to the user’s search intent behind the search query. Google, YouTube, Bing, DuckDuckGo, and Yahoo! are examples of some of the most popular search engines.

Now I understand that’s a lot of jargon to digest if you are not too technical, or have never heard of those terms before. But, don’t worry as I’m going to break everything down to the simplest form for you to consume it as effortlessly as possible.

There are a few important keywords used in the above definition of a search engine, and it’s crucial for you to really understand them deeply if you want to better understand how search engines work.

Search Index: The search index is equivalent to the index that we see at the beginning of a book. Yes, we are talking about the contents which contain a list of all the topics that are covered in the book. Similarly, Indexes contain the information on all the websites that Google (or any other search engine) was able to find. If a website is not in a search engine’s index, users will not be able to find it. An index is a database used by search engines to display search results to the user.

Search query: A search query is anything you type into that search box in search engines. Examples include, “ how search engines work”, “what is search query”, “what is indexing”, “best SEO expert near me”, and so on.

Search Intent: This basically means the real reason behind why you are carrying out a search, i.e, the intent behind your search.

For example, the search phrase “what is SEO” means the searcher is interested in knowing and learning about SEO.

On the other hand, the search phrase “best SEO expert to hire in Kolkata” clearly means the searcher wants to outsource their SEO work to an expert in Kolkata.

Now that we have got the basics out of the way, let us focus on understanding the way search engines work and the algorithm behind them.

It’s estimated that Google receives an average of 5.6 billion searches a day. That’s equal to 63000 searches per second. Now hold on for a moment and let that number sink in! For every one of those queries, the search engine trawls through more than 1 trillion individual pages live on the internet and select the best fitting results in less than a second.

The more convenient a search engine is to the user, the more complex structure and groundwork go on at the backend to make it reach that level.

It is important to note that Google, just like other search engines, is pretty secretive about the mechanisms behind those search results, however, we as marketers can benefit from knowing how search engines work using the ‘limited’ information that’s already available on the internet about search engine algorithms.

By understanding how search engines find, organize, and select results, you can better optimize your web pages to rank and show up higher in the SERP.

Site owners use Search Engine Optimization to improve the chances that content on their site will show up in search results. Content could be anything on your site. It could be pictures, written words, and/or videos.

Search engines use three basic mechanisms:

  • Web Crawlers
  • Search index
  • Search Algorithms

How do Search Engines Crawl, Index, and Rank Content?

How Search Engines Work

You type in a keyword, hit that search button, and you get a list of relevant pages returned on your screen in a fraction of a second. Simple, isn’t it? Well, that’s just from the outside.

Never let that lightning-fast information exchange deceive you into thinking that, whatever computational heavy lifting goes on backstage just after you hit the search button until the search engine returns you a list of results, is just as simple.

The hard work starts way before you make a search. Search engines work round-the-clock, gathering information from the billions of websites worldwide and organizing that information, so it’s easy to find. This is a three-step process of first crawling web pages, indexing them, then ranking them with search algorithms.

1. Crawling: Search engines use programs, called spiders, bots or crawlers, to scour the web for information. Crawlers start out with a list of websites. Algorithms, sets of computational rules, automatically decide which of these sites to crawl. The algorithms also dictate how many pages to crawl and how frequently. They look over the code/content for each URL they find. Crawlers visit each site on the list systematically, following links through tags to jump to internal or external pages. Over time, the crawlers build an ever-expanding map of interlinked pages.

What does this mean to you? Well, this means you need to ensure that your website is easily accessible to these crawlers. Because if it’s not, then these bots can’t crawl your site. And if they can’t crawl your site, they can’t index it, and that means your site won’t appear in search results.

If you’re not sure whether your site is accessible to crawlers, use a Site Audit tool to check it out. The tool catches accessibility issues and gives advice on how to fix them.

[Ps: If your site is not accessible to Search engines, Technical SEO services from FuelDigital are at your disposal to ensure that search engines can crawl your site.]

2. Indexing: After finding a page, a bot renders it similar to the way your browser does. That means the bot should “see” what you see, including images, videos, or other types of dynamic page content.

The bot organizes this content into categories, including images, CSS and HTML, text and keywords, etc. This process allows the crawler to “understand” what’s on the page, a necessary precursor to deciding for which keyword searches the page is relevant.

Search engines then store this information in an index, a giant database with a catalogue entry for every word seen on every webpage indexed. Once a page is in the index, it’s in the running to be displayed as a result of relevant queries.

Google’s index, the Caffeine Index, takes up around 100,000,000 gigabytes and fills “server farms,” thousands of computers that never get turned off, around the globe.

If you want to know what crawlers see when they land on your site, use the URL Inspection Tool. If you don’t want crawlers to show every page of your site in SERPs, like author pages or pagination pages, use a robots.txt file to control access by telling bots which pages they can crawl.

3. Ranking: In the final step, search engines, using their search algorithms, sort through indexed information and returns the pieces of content that will best answer a searcher’s query. This means that results are sorted by most relevant to least relevant.

Algorithms use numerous factors to define the quality of the pages in their index. Google leverages a whole series of algorithms to rank relevant results. Many of the ranking factors used in these algorithms analyze the general popularity of a piece of content and even the qualitative experience, like backlink quality, content freshness, & page load time among many others, that users have when they land on the page.

To make sure that the algorithms are doing their job properly, Google uses human Search Quality Raters to test and refine the algorithm. This is one of the few times when humans, not programs, are involved in how search engines work.

How do search engines personalize search results?

How do search engines personalize search results?

Did you know that Google’s search algorithm uses more than 200 factors to rank websites?

Search engines understand that different results appeal to different people. That’s why they tailor their results for each user.

If you’ve ever searched for the same thing on multiple devices or browsers, you’ve probably seen the effects of this personalization. Results often show up in different positions depending on various factors.

It’s because of this personalization that if you’re doing SEO, you’re better off using a dedicated tool to track ranking positions.

Information about your language in search settings, location, and search history helps search engines personalize the search results to your needs.


Understanding how search engines work is the first step towards ranking higher in Google and getting more traffic. If search engines can’t find, crawl and index your pages, you’re dead in the water before you even start. Next time when you create a fresh piece of content for your site, always keep the goal of search engines in mind. Their goal is to return only the most useful and relevant user to the searcher. The best way is to begin by optimizing your website for SEO. Sending the right signals to search engines guarantees that your pages appear in results pages relevant to your business.

[PS: For a no-obligation chat about building your online presence and setting up your website for SEO success, feel free to get in touch with us today by clicking here.]