Duplicate content

Duplicate content is the same or nearly the same text appearing at more than one address.

In a little more detail

It is rarely a penalty and often a dilution: machines have to pick one version to trust, and picking is something you would rather do yourself.

Related terms

Canonical: A canonical tag tells a search engine which version of a page is the real one when several addresses show the same content.
Index: The index is the searchable copy of the web a search engine keeps. If a page is not in it, that page cannot appear in results.

See it on your own site

The scan reads your site the way AI search does and reports where you stand on this and sixteen other checks.