Canonical tag
A canonical tag tells search engines which URL is the main version when the same or very similar content lives at several addresses.
Why it matters
Duplicates split signals and can make the wrong page rank; canonicals consolidate them.
Watch out
Different language versions are not duplicates; use hreflang for them.
Frequently asked questions
Does Google always follow it?
It is a hint; conflicting signals can lead Google to choose another page.