Indexability refers to whether a given page can be added to a search engine’s index. A page may be crawlable — reachable by a bot — yet still unindexable. Common causes of non-indexability include a noindex directive in the meta robots tag or HTTP header, a disallowed URL in robots.txt that prevents crawling (which also prevents indexing), a canonical tag pointing to a different URL, or a page returning a non-200 HTTP status. Thin content, duplicate content, and poor quality can also lead Google to choose not to index a page even when no explicit blocking is in place. Auditing indexability — using tools like Google Search Console’s Coverage report or crawlers like Screaming Frog — is a foundational step in any technical SEO review.