What a search engine is
What Is a Search Engine? Definition, Types and How They Work
A search engine is an automated information retrieval system that discovers, catalogs, and ranks web documents to satisfy user queries. It maintains a massive, independent index of billions of pages using automated crawlers, inverted indices, and ranking algorithms, operating separately from the web browsers and databases that connect to it.
Articles in this guide
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What is a search engine (definition, examples, how it differs from a website)
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How search engines work: crawling, indexing, ranking and serving
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Parts of a search engine: crawler, parser, indexer, ranker, interface
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Search engine architecture explained with a diagram
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Types of search engines: crawler-based, directory, hybrid, metasearch, vertical
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Search engine vs web browser
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Search engine vs website vs web page
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Search engine vs database: what is actually different
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Search engine vs web directory
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What is a metasearch engine
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What is a vertical search engine
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Federated search explained
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Enterprise search vs web search
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History of search engines: Archie to AI Overviews
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Who invented the search engine
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Search engine timeline 1990 to 2026
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How search engines make money
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Search engine market share 2026
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Surface web vs deep web vs dark web search
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Information retrieval basics for beginners
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What is a search index
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Why search engines matter for businesses and researchers