# How Search Engines Work — SEO for Developers

Source: https://www.geekswithgeeks.com/en/seo-developers/seo-search-engines

> Understanding crawling, indexing, and ranking to optimize for search visibility.

## Crawling and indexing

Search engines use **bots (crawlers)** to visit web pages, follow links, and read content. The content is then stored in a massive **index**. If a crawler can't reach your page or parse its content, it won't be indexed — and won't appear in search results.

## Ranking signals

Ranking depends on **hundreds of signals**: page speed, mobile-friendliness, content quality, backlinks, user experience, and freshness. Google's Core Web Vitals (LCP, FID, CLS) are critical. The goal: rank your site for queries your content answers.

## Developers' role in search visibility

You control the technical signals: load time, mobile rendering, structured data, sitemap, robots.txt, and redirects. A site that's technically perfect but has poor content won't rank; one with great content but broken markup also won't rank. Both matter.