Canonical Tags

 



A canonical tag is a small piece of code embedded into a webpage that can help search engines deal with multiple versions of the same page. In early 2009, three major search engines agreed to use the canonical tag to help deal with duplicate content on the web. Canonical tags are assigned with a simple HTML element in the page’s source code — also called a rel=canonical element, the code looks something like this: An example of how to implement a canonical tag instruction. The canonical URL, (also often referred to as rel=canonical, or the canonical tag, and other names) is what search engines refer to when they see multiple versions of a page on your website or even around the web. It is now used to solve some complicated duplicate content issues and is sometimes a better tool to use than a 301 redirect. A canonical tag is a signal in a web page which simply says: “I’m a copy of this other web page which can be found over there This HTML element is added into the code of a page and helps prevent duplicate content issues by telling Google and other search engines the preferred version of a page.

A canonical link element is an HTML element that helps webmasters prevent duplicate content issues in search engine optimization by specifying the 'canonical' or 'preferred' version of a web page. It is described in RFC 6596, which went live in April 2012.[1][2]

Purpose[edit]

A major problem for search engines is to determine the original source for documents that are available on multiple URLs. Content duplication can happen in many ways, including:[3]

Canonical Tags For Ecommerce

  • Duplication due to GET-parameters
  • Duplication with multiple URLs due to CMS
  • Duplication due to accessibility on different hosts/protocols
  • Duplication due to print versions of websites

Duplicate content issues occur when the same content is accessible from multiple URLs.[4] For example, http://www.example.com/page.html would be considered by search engines to be an entirely different page from http://www.example.com/page.html?parameter=1, even though both URLs may reference the same content.[5][6]

In February 2009, Google, Yahoo and Microsoft announced support for the canonical link element, which can be inserted into the <head> section of a web page, to allow webmasters to prevent these issues.[7] The canonical link element helps webmasters make clear to the search engines which page should be credited as the original.

How search engines handle rel=canonical[edit]

Search engines try to utilize canonical link definitions as an output filter for their search results. If multiple URLs contain the same content in the result set, the canonical link URL definitions will likely be incorporated to determine the original source of the content. ″For example, when Google finds identical content instances, it decides to show one of them. Its choice of the resource to display in the search results will depend upon the search query.″[8][citation needed]

According to Google, the canonical link element is not considered to be a directive, but rather a hint that the ranking algorithm will 'honor strongly.'[1][9]

While the canonical link element has its benefits, Matt Cutts, then the head of Google's webspam team, has said that the search engine prefers the use of 301 redirects. Cutts said the preference for redirects is because Google's spiders can choose to ignore a canonical link element if they deem it more beneficial to do so.[10]

Implementation[edit]

Semantic tag[edit]

The canonical link element can be either used in the semantic HTML <head /> or sent with the HTTP header of a document. For non HTML documents, the HTTP header is an alternate way to set a canonical URL.[3][11]

Canonical TagsTags

By the HTML 5 standard, the <linkrel='canonical'href='http://example.com/'> HTML element must be within the <head /> section of the document.[12]

Self-hyperlink[edit]

Some sites such as Stack Overflow[13] have on-page hyperlinks which link to a clean URL of themselves. Usability benefits are facilitating copying the hyperlink target URL or title if the browser or a browser extension offers a Copy link textcontext menu option for hyperlinks, the ability for the original URL to be retrieved from a saved page if not stored by the browser into a comment inside the file, as well as the ability to duplicate the opened page into a new tab right next to the currently opened one if the browser lacks such a feature.[14][13]

Examples[edit]

HTML[edit]

Below you can see an example of HTML code that utilises the rel=canonical inside the <head> tags. The code could be used on a page such as https://example.com/page.php?parameter=1to tell search engines that the https://example.com/page.php is the preferred version of the webpage.

Canonical Tags Seo

HTTP[edit]

See also[edit]

References[edit]

Canonical Tags

  1. ^ abKupke, Joachim (2009-02-12). 'Specify your canonical'. Google. Retrieved 2012-08-02.
  2. ^Cutts, Matt (2009-02-15). 'Learn about the Canonical Link Element in 5 minutes'. Retrieved 2012-08-02.
  3. ^ ab'Link rel=canonical: How to do URL canonicalization right'. Audisto GmbH. Retrieved 2015-10-06.
  4. ^'Duplicate content'. Google. Retrieved 2012-08-02.
  5. ^Biswas, Kushal. 'Canonical Issue and How to Use Canonical Tag – The Proper Way'. RevenueI. Archived from the original on 14 June 2016. Retrieved 18 June 2015.
  6. ^Zadro, Dario. 'Rel=Canonical - A Beginners Guide to Canonical Tags - Where and When to Use Them'. Zadro Web. Retrieved 18 June 2015.
  7. ^Fox, Vanessa (2009-02-12). 'Google, Yahoo & Microsoft Unite On 'Canonical Tag' To Reduce Duplicate Content Clutter'. Search Engine Land. Retrieved 2012-08-02.
  8. ^How Google And Other Search Engines Manage Canonical Links | http://seomediax.com/seo/how-google-and-other-search-engines-manage-canonical-links/
  9. ^'Consolidate duplicate URLs - Search Console Help'. support.google.com.
  10. ^Cutts, Matt (2011-05-16). 'A rel [equals] canonical corner case'. Retrieved 2012-08-02.
  11. ^'Consolidate duplicate URLs - Search Console Help'. support.google.com.
  12. ^'HTML link tag'. www.w3schools.com. Retrieved 2019-01-07.
  13. ^ ab'Why does the question title link to itself on the answer page?'. Meta Stack Exchange. 2010-04-23.
  14. ^'3 FireFox Addons to Easier Copy Links and Anchor Texts'. Search Engine Journal. 7 January 2011.

Canonical Tags Webflow

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