When you visit a web, sometimes you just want to obtain information from the web. However, sometimes, you may want to know which server the web uses, which programming language the programmers use, which CMS they use. You may obtain this information from the server response. Here is a simple tool that helps you to find out the answer - Whaweb(http://www.morningstarsecurity.com/research/whatweb).
This is written with Ruby and simply type
$./whatweb url
It will show you the relevant information such as web server.
