To avoid duplicate content in search engines you can force users to use either the www or the non-www version of your website domain. This avoids search engines such as Google indexing two versions of your domain, something which is quite common because people link to both www and on-www versions of a domain (known as the www/non-www canonical issue).
It really doesn’t matter if you use www.yoursite.com or yoursite.com. I personally use www on most sites I own however many people prefer to drop it, it’s really up to you.
Force users to use http://www.yoursite.com
To force users to use the www version of your domain all you have to do is add the following code to your .htaccess file (just replace yoursite.com with your domain name).
# Redirect non-www urls to www
RewriteEngine on
RewriteCond %{HTTP_HOST} !^www\.yoursite\.com
RewriteRule (.*) http://www.yoursite.com/$1 [R=301,L]
Alternatively you can use :
# Redirect non-www urls to www
RewriteEngine on
RewriteCond %{HTTP_HOST} ^example\.com [NC]
RewriteRule (.*) http://www.example.com/$1 [R=301,L]
Force users to use http://yoursite.com
To force users to use the non www version of your domain all you have to do is add the following code to your .htaccess file (just replace yoursite.com with your domain name).
# Redirect www urls to non-www
RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\.yoursite\.com [NC]
RewriteRule (.*) http://yoursite.com/$1 [R=301,L]
Alternatively you can use :
# Redirect www urls to non-www
RewriteEngine on
RewriteCond %{HTTP_HOST} !^example\.com
RewriteRule (.*) http://example.com/$1 [R=301,L]
