If you are running a Multisites or Subdomains sites this .htaccess RewriteRule code might come in handy specially for purpose of SEO. You can clean up your URL from http://www.yourdomain.com to http://yourdomain.com and remove the “www” with 301 redirect to non-www.
RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
RewriteRule ^(.*)$ http://%1/$1 [L,R=301]
RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
RewriteRule ^(.*)$ http://%1/$1 [L,R=301]
If you want to add the www to URLs check this code out.
