8th April 2021

How Do Search Engines Work? A Beginner’s Guide

Hannah Spelman

Sure, you’ve been using Google for years, Bing is favourited on your browser, and you check Yahoo daily… but do you actually know how these search engines work? With 93% of all online experiences beginning with a search engine, it’s important to fully understand their purpose, especially if you’re a business looking to use search engine optimisation (SEO) in your digital marketing strategies. Read on as we guide you through the basics of search engines.

Wait, what is a search engine?

In order to find out how search engines work, you first need to know their purpose. Search engines have often been labeled the internet’s answer machine. They are programs that take keywords given by a user, identify the user’s intent, and find related content online, aiming to present these results as quickly as possible.

They do this by working through three primary functions: crawling, indexing, and ranking. The goal for many sites is to appear in the first few results for the most popular keywords related to their business, as it leads to more brand awareness.

More than 90% of web searches happen on Google suggesting that knowing how Google finds and ranks content is vital in being able to create websites that show up in the search results. However, a page that ranks highly for a search query in Google may not rank highly for the same query in Bing so it’s important to consider a range of search engines when publishing content online.


The first step search engines will take is to crawl the web by using robots (which are referred to as ‘crawlers’ or ‘spiders’) to scour the internet and information archives to find content. This can include image and video files, and both new and updated pages. The search engine will download these pages and add them to an index to look at later.

The web crawler then follows all the links on the page, repeating the process of copying, indexing and following the links. Just as a crawler needs to discover your site via links from other sites, it needs a path of links on your own site to help guide it. Internal links can be a useful way for a search engine to access all of a website’s data and understand their relative importance.


An index is a huge database of all the content that search engines have discovered and deems good enough to serve up to users. The web pages found by the search engines are added into an index along with relevant contents of each URL, such as:

  • Keywords discovered within the page’s content - what topics does the page cover?
  • Type of content that is being crawled - what is included on the page?
  • Freshness of the page - how recently was it updated?
  • Previous user engagement of the page - how do people interact with the page?

These relevance signals help algorithms assess whether a website answers a user’s query and fulfills their intent. Following SEO best practices could help search engines better understand a website’s content and allow it to rank higher for the right queries.

However, sometimes a page might not be indexed, for example, if the search engine algorithms find the page too low quality, or containing duplicate content, they may choose to hide it from users.

Once a page is in the index, it’s in the running to be displayed as a result to relevant queries. When someone performs a search, search engines scour their index for highly relevant content and then ranks the content aiming to solve the searcher's query. The higher a website is ranked, the more relevant the search engine believes that site is to the query.


When a user makes a search on a search engine, it will review a number of key factors to then determine which pages should be returned for the user's query. They display them in order of what they believe is the most relevant to the searcher's query, which is known as the process of ranking. This combination of key factors makes up the search engine's algorithms and is what determines where a page should rank.

What are search engine ranking factors?

These differ between search engines but one common thread is the fact that there are multiple factors - Google, for example, has over 200 ranking factors. Google’s algorithm will look at these ranking factors and then will order the search results based on how well each page answers those factors.

Some factors are out of our control, such as the age of the page, but others that we can control, including on-page SEO, do play a part in where a website might rank.

RankBrain is considered one of Google’s most important factors; the machine learning system in Google’s core algorithm attempts to understand the meaning behind queries, customising a user’s search results to provide the most relevant content. If RankBrain notices a lower ranking URL provides a better result to users than the higher ranking URLs, it will adjust the results so that the most relevant result ranks higher.

Backlinks play a large role in SEO and ensuring that search engines understand the importance of a page. Google’s PageRank is perhaps one of the most well-known ranking algorithms, but most search engines use a similar metric to calculate the number of links pointing to a page and how trustworthy these are. One good link from an authoritative domain can be more impactful than millions of low-quality links; the trust scores and quality of backlinks matter more than the volume. There are many spammy sites that try to game their way to the top of search results by buying links that pass PageRank, but this isn’t organic.

Improving content is one of the main ways to organically increase onsite traffic and rank higher; providing relevant content means it's more likely to be seen. Recently, there’s been a shift away from keyword-focused content towards more relevant content that shows expertise, authority, and trust. Some other ranking factors include:

What I-COM Can Do For You

Our SEO experts want to help you and your business improve the organic performance of your website. Using techniques such as link building, keyword research, meta creation, and content optimisation, we can assist you in getting the exposure you need.

If you have any questions about search engines, or if you want to know how our SEO services can benefit you, give us a call today on 0161 402 3170 or use our contact form.