When the user clicks the button, the action method is performed as a request from the users browser, if you'd requested it as GET, the browser will send every bit of info presented in the form as part of the url, if it is required as POST, the browser will include the info in the body of the request, where serverside you can obtain it from teh global POST var.
http://en.wikipedia.org/wiki/Hyperte...equest_methods