Web Search Algorithm Basics


In this article, we will explore the basics of web search algorithms and how they play a crucial role in search engine functionality. We will discuss what search engines are, their purpose, and how they generate revenue. Additionally, we will delve into the process of building search indexes and the factors that influence the ranking of web pages. Finally, we will examine how search engines personalise search results based on user information.

Search Engines: An Overview

Search engines are searchable databases that contain information about web content. They consist of two main components:

  1. Search Index: A digital library that stores information about webpages.
  2. Search Algorithm(s): Computer program(s) designed to match search queries with relevant results from the search index.

The primary objective of search engines is to provide users with the most accurate and relevant search results. By delivering high-quality results, search engines attract more users and gain market share.

Revenue Generation for Search Engines

Search engines generate revenue through two types of search results:

  1. Organic Results: These results are derived from the search index and cannot be influenced by payment. Websites cannot pay to appear in organic search results.
  2. Paid Results: Advertisers can pay to have their webpages displayed as paid search results. Each time a user clicks on a paid search result, the advertiser pays the search engine. This advertising model is known as pay-per-click (PPC) and is a significant source of revenue for search engines.

The market share of a search engine directly impacts its revenue potential. More users translate to more ad clicks and increased revenue.

Building a Search Index

Each search engine follows a specific process to build its search index. While the exact details may vary, we will focus on Google’s simplified process as an example.

1. URLs

The process begins with a list of known URLs. Google discovers these URLs through various methods, including:

  • Backlinks: If a new page is linked from an existing page in Google’s index, it can be discovered.
  • Sitemaps: Website owners can provide Google with a sitemap, which outlines important pages and files on their site.
  • URL Submissions: Site owners can request Google to crawl specific URLs using Google Search Console.

2. Crawling

Crawling involves a computer bot, commonly known as a spider or crawler, visiting and downloading the known URLs. Google’s crawler is called Googlebot. It retrieves the content of webpages, including HTML, CSS, Javascript, and other resources.

3. Processing and Rendering

During processing, Google analyses the crawled pages to extract relevant information. To accomplish this, it renders the page by executing its underlying code to understand its visual appearance and functionality. The process involves extracting links and storing content for indexing.

4. Indexing

Indexing is the stage where the processed information from crawled pages is added to the search index. Search engines like Google and Bing index webpages to make them discoverable to users. Being indexed is crucial for a website to appear in search results.

It’s noteworthy that Google dominates the search engine market, holding a staggering 91.43% market share. As a result, it can drive significant traffic to websites compared to other search engines.

Search Engine Ranking Factors

Discovering, crawling, and indexing content are only the initial steps in the search engine process. Search engines must also rank the search results based on their relevance to the user’s query. This task is accomplished using search algorithms.

What are Search Algorithms?

Search algorithms are formulas or sets of rules that match and rank relevant results from the search index. While the exact details of Google’s algorithms remain undisclosed, several key ranking factors are known. Let’s explore a few of them.

Backlinks are links from one webpage to another. They are amongst Google’s strongest ranking factors. Websites with high-quality backlinks often outrank those with numerous low-quality backlinks. A study of over a billion pages revealed a strong correlation between linking domains and organic traffic.

You can use Ahrefs’ Webmaster Tools to check the backlinks to your website for free. With the tool, you can gain insights into your backlink profile and understand how it impacts your website’s performance.

2. Relevance

Relevance refers to the usefulness of a search result for the user. Google determines relevance in various ways. At a basic level, it looks for pages containing keywords matching the search query. Additionally, Google considers interaction data to determine if users found a particular result helpful.

3. Freshness

Freshness is a query-dependent ranking factor. It holds more significance for search queries that require up-to-date information. For instance, a search for “new Netflix series” would prioritise recently published content, while a search for “how to solve a Rubik’s Cube” would not necessarily prioritise recent results.

4. Page Speed

Page speed is a ranking factor for both desktop and mobile searches. However, it tends to have a more negative impact on slow-loading pages rather than a positive influence on exceptionally fast ones.

Ahrefs’ Webmaster Tools can help you assess your page speed for free. With the Performance report, you can crawl your website and gain insights into its speed. The less red you see in the report, the better your page speed.

5. Mobile-Friendliness

Since Google’s switch to mobile-first indexing in 2019, mobile-friendliness has become a ranking factor for both mobile and desktop searches. Websites that are optimised for mobile devices are more likely to rank higher in search results.

Personalisation of Search Results

Google personalises search results based on various user-specific factors. This customisation is aimed at providing a more tailored search experience. Let’s explore some of the factors that influence personalised search results.

1. Location

Google utilises a user’s location to personalise search results, especially for queries with local intent. For example, when searching for “Italian restaurant,” the displayed results will predominantly be from or about local restaurants. Google understands that users are more likely to choose nearby options for dining.

2. Language

Google recognises the importance of displaying search results in the appropriate language. Instead of showing English results to Spanish-speaking users, it prioritises localised versions of content if available.

3. Search History

Google saves user search history and activity to provide a more personalised search experience. This includes the websites visited and actions performed by the user. Although it is possible to opt out of personalised search, most users generally do not.


Understanding the basics of web search algorithms is crucial for website owners and digital marketers aiming to optimise their online presence. Search engines employ complex processes to build search indexes, rank webpages, and personalise search results. By considering key ranking factors and catering to personalised searches, website owners can enhance their visibility and attract relevant organic traffic.

Remember, Google dominates the search engine market, making it essential to optimise for its algorithms. By focusing on factors such as backlinks, relevance, freshness, page speed, and mobile-friendliness, website owners can improve their chances of ranking higher in search results.

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