Inside the research
Three jobs, three different failure points
Crawling fetches a page, indexing analyzes and stores searchable information, and serving retrieves and ranks candidates for a query. An indexed URL can still rarely appear. Separate those stages before interpreting a Search Console status as the complete diagnosis.
Why the index starts with words
The explainer uses three imaginary travel pages to show an inverted index: each term points to the pages containing it. Positions support phrase and proximity matching. Passage understanding can help a relevant section contribute to a page match, while semantic retrieval adds a way to find related meaning.
The practical review
Keep exact names accurate, make important facts available as text, give each section a clear question and useful answer, and investigate near-duplicates. The diagrams simplify information-retrieval concepts; they do not expose Google’s proprietary index architecture.