Redirect blogger non-www to www domain version

You may know and may not, that every website or blog should have one preferred domain no matter it is domain.com or www.domain.com. Therefore always one version should redirects to another version from SEO point of view. If not, i.e. if you can open both domain versions in a browser, it mean there are two equal entities on the web, with same content, with same everything.
Search engines and especially Google, don't like that. Search engines sees two different pages on the web, they spent time and resources, and imagine how many pages are on the web and how many may have issue like this.
It means a lot of extra resources and sometimes bad user experience. For that reason, Google penalize those pages that do not redirect one domain version, to their preferred. In SEO this is called duplicate content issue.
In Blogger, this can be set very easily. If you already have a domain name, and set the name servers, and everything is OK, when opening your domain with and without www, you can see that there are two same version of your website.
So go in Blogger, Settings and in the section Publishing, click edit on your address. You can see from the image bellow that the check box for redirection is clicked. You should do the same as that will redirect your non-www version to www.

Now open a browser and type yourdomain.com. You will see that it will redirect to www.domain.com.

Wait for a five minutes for changes to apply to all of your posts and pages.

That's it. With this simple tip, you prevent penalizing from the search engines and mainly from Google, for having duplicate content issue.