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How does a search engine work?
Quick answer
A search engine works by constantly crawling the web, indexing what it finds, and ranking pages to answer your queries. When you search, it doesn't scan the live web — it instantly sorts its pre-built index to surface the most relevant results.
Step by step
- 'Crawler' bots follow links to discover web pages.
- It stores what it finds in a giant searchable index.
- When you search, it ranks indexed pages for relevance.
- Ranking weighs keywords, links, quality, and many other signals.
- It returns results in a fraction of a second.
People also ask
How does a search engine find results so fast?
It searches its own pre-built index of the web, not the live internet, so it just sorts already-gathered data in milliseconds.
How does a search engine decide the order of results?
Complex ranking algorithms weigh relevance, page quality, links, freshness, and user signals to estimate which pages best answer your query.
What is web crawling?
Automated bots following links from page to page to discover and revisit content, which the engine then indexes for searching.
What is crawling and indexing?
Crawling is discovering pages via links; indexing is storing and organizing their content so it can be searched instantly.
How do search engines rank pages?
By many signals — relevance to the query, content quality, links from other sites, freshness, and user experience.
What is SEO?
Search Engine Optimization: improving a site so search engines understand it and rank it higher for relevant queries.
Part of the guide: How the Internet Works →