Hidden fields often store a default value, or have their value changed by a JavaScript.

Edit code and click me	Your Result (Some examples do not work in Google Chrome):
<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> </head> <body> <form action="http://xhtml.co.il/tryit/html/form_action.php" method="get"> Email: <input type="text" name="email" /><br /> <input type="hidden" name="country" value="Norway" /> <input type="submit" value="Submit" /> </form> <p>Click on the submit button, and the input will be sent to a page on the server called "form_action.php".</p> </body> </html>
Edit the code above and click to see the result	www.xhtml.co.il - Try it yourself