How Search Engines Work: Basic Algorithms

Want to optimize your site the right way and set yourself up for success? Then it’s critical to know how search engines operate today.
Search engines are a significant factor in everyday life. From recipes to the news, from images to videos, we use search engines like Google to help us with information. But what are search engines, really? How do they work? What actually is the process for information retrieval?
Search engines have to review millions of web pages to provide the most useful information for each search query. They must then decide how to organize that information and present it to the search user.
Google and other search engines prioritize their search users’ experience over anything. Therefore, their goal is to provide the best results for every query.
So for search users, it’s simple. They enter their query, and search engines look through their index of web pages to find the best matches. Those matches are then ranked by an algorithm and displayed in search engine results pages (SERPs).
For marketers, search engines are tools for getting eyes on your content or on your products. But how can you optimize your site to set it up for success? What is the difference between crawling, indexing, and ranking, and why do you need to know?
Google and other search engines work using a variety of different elements. First, they use web crawlers to crawl pages to get data. Next, they index them to be retrieved in future search queries.
Ultimately, they rank the indexed content based on a variety of factors. These factors are part of the algorithm to determine what results are relevant and which results are quality.
Over time, search engines have become more complicated. They can answer questions directly on search engine results pages, surface different content types, and even change the SERPs to reflect queries.
They’ve also been able to understand more diverse web sites. All of this has created an answer engine ecosystem that changes daily.
In 2020, Google ran over 600,000 experiments to make improvements to the Search algorithm. Live traffic experiments allow Google to test new search features before they are rolled out globally.
Understanding how these algorithms and features work is fundamental to making sure your content gets seen on Google. It will also help you understand the results you see when you perform searches yourself.
How Search Engines Work, written by VIP contributor Dave Davies, tackles the following questions:

What are search engines crawlers? How do search engines use crawlers?

How do crawlers discover and index new pages?

What is rendering, and why is it important to search?

What are search algorithms, and how do they play into search?

What do you need to know about ranking? How do algorithms measure factors like quality and relevance?

How do search engines answer questions?

In partnership with HigherVisibility, we created this ebook for SEO pros who want to strengthen their technical SEO knowledge, and novices outside the field who want to better understand how search engines work as a part of our day to day lives.