This beginner's guide from Moz explains how search engines actually find, index, and rank web content.

It starts with the two core functions of any search engine: crawling the web and building an index.

The guide uses a subway system analogy, comparing web pages to stops connected by links.

You'll learn how search engine 'crawlers' or 'spiders' follow links to discover billions of interconnected pages.

It explains why link structure is so fundamental to how search engines understand the web.

The guide is written to make foundational SEO concepts accessible, even with zero prior experience.

It's widely regarded as one of the most approachable starting points for learning SEO.