Definition
A canonical URL is the preferred or "official" version of a webpage that search engines should index and display in search results when multiple URLs contain identical or very similar content.
Use Cases & Examples
When Multiple URLs Show the Same Content
Your website might accidentally create several different web addresses that all show identical content. For example, your homepage might be accessible at yoursite.com, www.yoursite.com, and yoursite.com/home. Canonical tags tell search engines which version is the “official” one to display in search results.
E-commerce Product Pages
Online stores often have products that can be reached through different paths. A single product might appear in multiple categories or have filtering options that create new URLs. Canonical tags ensure all the search engine credit goes to one main product page instead of being split across multiple addresses.
Blog Posts and Articles
Content management systems frequently create multiple ways to access the same article. A blog post might appear on your homepage, in category archives, and through tag pages. Canonical tags designate the main article URL as the primary version for search engines.