A canonical link element is an HTML element that helps webmasters prevent duplicate content issues by specifying the "canonical", or "preferred", version of a web page as part of search engine optimization.
Canonical tags define relationships between pages and tell search engines that a specific URL may be a duplicate of another page. This is important because having several pages indexed with identical or similar content can harm your ranking. Itâ€™s also annoying for users to click on multiple search results only to end up on pages with the same content.
As per the definition of canonical tags I can say these are the tags inserted in to header of HTML of your website and helps search engine bots to identify duplicate and original content.Canonical tags tell the search engine bots which pieces of contents are the first or primary ones and which are duplicates.
Itâ€™s appropriate to use a rel=canonical tag on very-near duplicate pages.You will use a rel=canonical tag, if you want to keep both pages for visitors, but only one of them should be considered by the search engines for search results.
If you have two or more pages with similar content,you van tell google which is your preffered page to show in the search engine results.this is referred to as your 'conanical' page. In this case we will use canonical tag and will tell search engine that content on both the pages is same to avoid any duplication issue and inform the search engine bot to rank page 1 in search engine compared to page 2.