You may want all visitors to your site using www in front of your domain name (www.yourdomain.com) instead of just your domain name (yourdomain.com). By implementing a simple .htaccess RewriteRule, visitors to yourdomain.com will see the URL change in their browser as they are redirected to the correct URL.
To redirect a URL such as “http://yourdomain.com/images/logo.png” to “http://www.yourdomain.com/images/logo.png” use:
Options +FollowSymLinks
RewriteEngine on
RewriteCond %{HTTP_HOST} ^yourdomain\.com
RewriteRule ^(.*)$ http://www.yourdomain.com/$1 [R=permanent,L]
In the RewriteRule code, the R=permanent sets the type of redirection (permanent is 301; the default is temporary or 302). The L makes this the last Rule to use and stops rewrite processing.