Most of sites in the internet has default www. as the sub domain ..  But it can access without www also. So what is the best practice .? It is better if you can maintain unique domain ..

You have a way to do this.  If you decide to maintain www.yourdomain.com ,When ever user type the domain without www. ,it should redirect to www.yourdomain.com . That redirection should be permanant (301) redirection.

This can be done using mod_rewrite , you have to insert few lines to .htaccess file.

RewriteCond %{HTTP_HOST} ^easywebtech.com [NC]
RewriteRule ^(.*)$ http://www.easywebtech.com/$1 [L,R=301]

You can browse http://easywebtech.com ,you will see it automatically redirects to the  http://www.easywebtech.com

[NC] – No case , this means ignore the case of the url .

[L,R=301]  L- last redirect , R=301  permanant redirection,

When you do this you will not be having two Google page ranks for these domains. Also this will avoid duplicate content  issues.