webserver and application server http://www.diffen.com/difference/Application_Server_vs_Web_Server http://www.differencebetween.com/difference-between-web-server-and-vs-database-server/ http://www.acunetix.com/websitesecurity/webserver-security/ http://www.questpond.com/ http://blog.csdn.net/keyeagle/article/details/6723408