# How Search Engines Work — SEO for Developers: Technical SEO and Core Web Vitals

Source: https://www.skillbyai.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**: relevance, content quality, backlinks, page speed, mobile-friendliness, user experience and freshness. Google's Core Web Vitals (LCP, INP, CLS) are part of page experience. The goal: rank for the 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.