How do crawlability and indexability affect rankings?

Crawlability and indexability are prerequisites for rankings: a page generally has to be discoverable first, then eligible to be stored in the search index, before it can compete to rank.

• Crawlability affects whether search engines can find and access the page in the first place; if a page can’t be crawled, it typically can’t be indexed or ranked.
• Indexability affects whether a crawled page can be included in the search engine’s index; if it’s blocked by things like noindex, canonicalisation to another URL, or similar technical signals, it may not appear in results even if it was crawled.
• Ranking comes after those steps: only pages that are crawlable and indexable can usually be evaluated for relevance and shown in search results.

In practical terms, poor crawlability or indexability can suppress rankings entirely because the page never gets the chance to compete.