Duplicate Content.

Duplicate content refers to substantive blocks of content that appear at multiple URLs: either within the same website (internal duplicates) or across different websites (external duplicates/syndication). Search engines must determine which version to index and rank, which can split link equity between duplicates and may result in neither version ranking as well as a consolidated version would.

Common Sources of Duplicate Content

Internal duplicate content is often technical in origin: www vs. non-www versions of URLs both being accessible; HTTP and HTTPS both serving content; URL parameters creating filtered/sorted versions of the same page (e-commerce filtering is a major source); printer-friendly page versions; session IDs in URLs; and content management systems generating multiple URL formats for the same content. Syndicated content published on multiple sites creates external duplicates.

Resolving Duplicate Content

Primary solutions: implement 301 redirects to consolidate accessible URL variants to one canonical version; use canonical tags to signal the preferred URL without redirecting; configure URL parameter handling in Google Search Console; use consistent internal linking to the canonical URL; and for external syndication, request that publishers add a canonical tag pointing to your original. Proper implementation prevents the ranking dilution that duplicate content causes.