Canonical Tag
A canonical tag (rel=canonical) is an HTML link element that tells search engines which URL is the preferred version among duplicate or near-duplicate pages. Engines treat it as a strong hint, not a directive, consolidating ranking signals to the chosen canonical URL.
Why It Matters
Duplicate content splits link equity and can leave engines guessing which version to rank. A correct canonical consolidates signals to one URL, preventing self-competition and helping the right page earn rankings for its target queries.
Common Mistake
Pointing canonicals at the wrong page, at redirected or noindexed URLs, or at the homepage for every page. Also self-canonicalizing paginated or filtered pages incorrectly, which tells engines to drop pages you actually want indexed.