Redirect your site to always use www
For make it easy measuring traffic or with sessions cookies for login, you can redirect all calls for example.com to www.example.com by adding the following script to a .htaccess file in root of your site.
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]
</IfModule>Probably you already have an .htaccess file and you just have to uncomment the code and change example.com to your domainname.