TECHNICAL · SEO GLOSSARY
Indexability
Whether a web page can be added to Google\'s search index and therefore appear in search results — determined by the absence of indexation barriers: `noindex` directives, canonical tags pointing elsewhere, HTTP errors (4xx/5xx), robots.txt disallows blocking crawl, or redirect loops.
Definition
Indexability is the property of a page that determines whether Google will include it in its search index — the database of pages that can appear in search results. A page must be both crawlable (Googlebot can access it) and indexable (no directive prevents indexation) to appear in search results. Indexability barriers: **`noindex` meta tag** — `<meta name="robots" content="noindex">` in the page\'s `<head>` tells Google not to index the page. The page is still crawlable (Googlebot reads it to find the noindex directive) but won\'t appear in search results. **`noindex` in X-Robots-Tag HTTP header** — the server sends `X-Robots-Tag: noindex` in the response headers, functionally identical to the meta tag. **Canonical tag pointing elsewhere** — `<link rel="canonical" href="https://example.com/other-page">` signals that the canonical version is the other page; Google indexes the canonical, not the page carrying the non-self-referential canonical. **Robots.txt disallow** — blocks Googlebot from crawling the page. Google can\'t read a disallowed page to find the noindex directive; a page that\'s disallowed can be inferred-indexed from external links (it appears in results but without a title or description). **4xx HTTP responses** — the page doesn\'t exist (404) or is forbidden (403); Google drops 404-returning URLs from its index after repeated encounters. **5xx HTTP responses** — server errors; Google will retry and eventually drop the URL if the 5xx persists. **Redirect to another URL** — the original URL is not indexed; the destination URL is indexed instead. Common indexability mistakes: accidentally applying `noindex` to categories, tag pages, or the entire site via a misconfigured SEO plugin; using a `disallow: /` in robots.txt that blocks all crawling (often left from staging environments); forgetting to update the canonical from staging to production after a site launch.
Why it matters for SEO
A page that isn\'t indexed cannot rank, regardless of how good its content or how many links point to it. Indexability issues are therefore the highest-priority technical SEO problems to identify and fix — they\'re the most direct possible barrier between SEO work and results. The most catastrophic indexability failure is an accidental site-wide `noindex` directive or `robots.txt disallow: /` on a production site — these take a site completely out of search results. GSC\'s Coverage report is the primary tool for monitoring indexability across the site, categorising all known pages into indexed, excluded (with reason), and error.
How DeepSEOAnalysis checks this
The audit checks indexability for every crawled page: reads the `<meta name="robots">` and `<meta name="googlebot">` tags, checks for `X-Robots-Tag` in the HTTP response headers, validates that the canonical tag is self-referential (or deliberately pointing to a different URL for a good reason), checks for redirect chains and their destinations, and records HTTP status codes. The robots.txt is also audited for disallow rules that might block important page categories — flagging patterns like `Disallow: /` or broad disallows that catch content pages.
Useful tools and resources
GLOSSARY
Related terms
technical
Noindex
A directive that tells search engines not to include a page in their index — implemented via a meta tag or HTTP header.
Read definition →technical
Canonical Tag
A canonical tag (rel="canonical") is an HTML link element that tells search engines which URL is the authoritative version of a page when duplicate or near-duplicate content exists at multiple URLs. It consolidates ranking signals from all duplicate variants to the canonical URL.
Read definition →technical
Robots.txt
A text file at the root of a domain that tells crawlers which pages or sections to access or avoid.
Read definition →technical
Crawl Budget
The number of pages Googlebot will crawl on a site within a given timeframe — determined by crawl rate limit and crawl demand.
Read definition →technical
Technical SEO
The discipline of optimising a website\'s infrastructure — crawlability, indexability, site speed, structured data, and security — so that search engines can discover, render, and understand pages correctly.
Read definition →technical
Google Search Console
Google\'s free tool for monitoring how your site appears in Google Search — showing impressions, clicks, CTR, average position, index coverage, and crawl errors.
Read definition →See how your site scores on Indexability.
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