Why is a canonical meta tag important?
A canonical meta tag specifies the definite URL of a page. If the same page of a website can be requested through different URLs, the risk of duplicated content is considerably increased. This means that the automatic indexer of a search engine detects that the page content can be found on several URLs on the website. Duplicated content could result in the found pages being sorted lower on the search engine results page (SERP).
A canonical meta tag is mainly used when dealing with large websites with a lot of (database driven) content. For smaller websites with just a few (static) pages, the use of a canonical meta tag becomes irrelevant.