Noindex and canonical tags solve different problems and are not interchangeable. Confusing them is one of the most common technical SEO mistakes we see in Canadian client audits. **Noindex** (`<meta name="robots" content="noindex">` or X-Robots-Tag HTTP header) explicitly instructs Google to exclude the page from the search index. Pages with noindex can still be crawled, can still pass link equity if they contain links, but will not appear in search results. Use noindex for: thank-you pages, internal admin pages, gated content you want to remain private, low-quality pages you don't want indexed but cannot delete, paginated archive pages where you want users to land on the main page. **Canonical tags** (`<link rel="canonical" href="https://example.com/preferred-url">`) tell Google that, when multiple URLs serve substantially similar content, a specific URL is the preferred version. Google may still index the non-canonical URL but will typically consolidate ranking signals (link equity, user signals) to the canonical URL. Use canonical for: parametrized URLs (filters, sort orders, tracking parameters that produce duplicate content), syndicated content that exists on multiple sites with permission, mobile/desktop URL variations, multilingual content where one language version should be the primary. **The most common mistakes:** using canonical to keep pages out of the index (it doesn't reliably do that — Google can ignore canonicals it disagrees with); using noindex on pages you also have canonical tags pointing to (Google may interpret the conflict in ways you don't want); using self-referential canonicals on pages you also want noindexed (just use noindex without canonical); using canonical to point to pages that are themselves canonicalized elsewhere (creates canonical chains that Google may ignore). For most Canadian small business sites, the practical rule is: use noindex aggressively for pages that should not appear in search; use canonical conservatively only for genuine duplicate-content scenarios; never use both on the same page.