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📘 How a search engine ranks pages

Follow crawling, indexing, retrieval, ranking signals, freshness, and serving results.

lessons

~20 min

to learn

🔬 Science

subject

Adults

level

Start the course →

What you’ll learn

Crawl
Fetch
Index
Inverted index
Query
Candidates
Signals
Links
Content
Freshness
Personalization
Serving
Snippets
Updates
Limits
Pipeline

Questions this course answers

What is crawling?

Crawlers request pages and follow discovery signals.

What happens during indexing?

Indexing prepares page information for later retrieval.

Why are candidates retrieved before ranking?

Efficient retrieval narrows the set that ranking evaluates.

What do ranking signals do?

Signals help automated systems order plausible candidates.

Why can search results change?

Recrawling and reindexing update the engine’s view of the web.

Grounded in trusted sources

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Every Wunder lesson is built from real, reputable sources — never invented.

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