Canonical Link Element Video Tutorial
Google and other search engines announced support for a canonical link element that can help site owners with duplicate content issues.
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Canonical Link Element Video Tutorial
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What is a canonical page? Why specify a canonical page?
A canonical page is the preferred version of a set of pages with highly similar content.
It's common for a site to have several pages listing the same set of products. For example, one page might display products sorted in alphabetical order, while other pages display the same products listed by price or by rating.
Read more about Canonical Link Element at Google Webmaster Help.