What are the best practices of preferred domain configuration?

Question

What are the best practices of "preferred domain" configuration?

Answer

Typically, any website is available on two URLs: with the www prefix (like in
www.example.com) and without it (like in
example.com).

In general, we recommend that you always redirect visitors to one of these URLs (typically to the non-www version). For example, after you set the Preferred domain to the non-www version (example.com), site visitors will be redirected to this URL even if they specify www.example.com in their browsers.

Refer to Plesk documentation for more details.