If you're concerned that Google's move to mobile first indexing might negatively affect your site's visibility and search engine ranking...
What is Canonicalisation?
There are many web design and SEO terms and phrases which we often get asked about as to their meaning.
Canonicalisation (canonicalization) is an internal content duplication issue which is created when the same page or content can be accessed from different URLs, commonly due to URLs not being standardised properly in the site. Here are some classic examples:
Content duplication of this kind can be quite a problem for large sites with lots of content, and they may get penalised as a result. You can combat canonicalisation of this kind by setting up and standardising your URLs properly, and by using 301-redirects (permanent redirection) to direct the user to the correct page. Any cached pages that a search engine has will update to the correct link if a 301-redirect is used.