How to redirect non-www URLs to www URLs in Apache

Below is the answer on how redirect your traffic to www URLs.

E.g.
http://domain.com -> http://www.domain.com
https://domain.com -> https://www.domain.com

Q:  Why would you need it?
A:  Search engines will regard those as different pages with duplicate content.
http://www.thesitewizard.com/apache/redirect-domain-www-subdomain.shtml

You can either put this code in .htaccess file or inside your site configuration under
/etc/httpd/conf/sites-enabled


Non-SSL redirection goes within <VirtualHost *:80> </VirtualHost>:

RewriteEngine on
RewriteCond %{HTTP_HOST} ^domain\.com
RewriteRule ^(.*)$ http://www.domain.com$1 [R=permanent,L]

SSL redirection goes within <VirtualHost *:443> </VirtualHost>:

RewriteEngine on
RewriteCond %{HTTP_HOST} ^domain\.com
RewriteRule ^(.*)$ https://www.domain.com$1 [R=permanent,L]