Definition

Duplicate content describes blocks of content that match or closely resemble each other at multiple URLs. Search engines have to choose one canonical version to index, and signals such as links and rankings may be split across the duplicates.

Duplicate content commonly arises from URL parameters, session IDs, http and https variants, www and non-www hosts, printer-friendly pages, syndication and faceted navigation. Google does not treat most duplication as a manual-action offence; instead it clusters the duplicates and selects a canonical URL using signals like sitemap inclusion, internal linking, redirects and rel=canonical annotations. Site owners can influence that selection by consolidating URLs with 301 redirects, declaring canonicals or noindexing low-value variants.

Examples

• Tracking parameters create duplicates

  An online store reaches the same product page via `/shoes/runner`, `/shoes/runner?utm_source=email` and `/shoes/runner?ref=affiliate`. Google clusters the three URLs and picks one canonical to display in results.

• Syndicated article on a partner site

  A news publisher republishes an article on a partner domain without a canonical pointing back to the original. Google has to decide which copy to show in Search, and the partner's version sometimes outranks the source.

Sources

• Google Search Central — Consolidate duplicate URLs

Related terms

• Canonical Tag
  An HTML element that tells search engines which URL is the master copy when the same or similar content exists at multiple addresses.
• 301 Redirect
  A permanent redirect — an HTTP 301 status code telling clients and search engines that a URL has moved permanently to a new location.
• Noindex
  A robots directive that tells search engines not to include a page in their index, even if the URL is publicly reachable.
• URL Parameters
  Key-value pairs appended to a URL after a question mark, used to filter, sort, track or otherwise vary the response without changing the path.
• Indexing
  The process by which a search engine analyses a fetched page and stores information about it so the page can later be returned in search results.

Where QueryCatch uses this

• SEO Audit
• Page Optimisation