Yet another kind of input is HIDDEN input.
<INPUT TYPE=HIDDEN NAME="FORMNAME" VALUE="Friend Form 1">
A HIDDEN input is a name/value pair which is returned to you but does not illustrates anywhere on the web page. The hidden input above is required for use with the mailto Formatter (MTF). This is how MTF identifies the forms it has to parse.
Assume you were a company attempting to generate leads for a new product. You have a standard form for collecting information that has name, phone, company, products interested in, etc. The only problem is there are six slightly distinct versions of the form in six different places. You need to make out what is coming from where and what to do?
You could add up a HIDDEN input to your forms such as:
<HTML>
<BODY>
<FORM METHOD=POST>
<INPUT TYPE=HIDDEN NAME="FORMNAME" VALUE="Version 1"> the first version
<INPUT TYPE=HIDDEN NAME="FORMNAME" VALUE="Version 2"> the second version
<INPUT TYPE=HIDDEN NAME="FORMNAME" VALUE="Version 3"> the third version
</FORM>
</HTML>
By the way, this doesn't matters what the name/value pair in the hidden input is (or any input for that matter).
<INPUT TYPE=HIDDEN NAME="E" VALUE="Mc^2"> HIDDEN inputs are also useful for cgi scripts. For instance, numerous Internet Service Providers have a script you can have your forms sent to. Then it sends the form back to you correctly formatted. The hidden input might be used to tell the cgi script that who you are, where to send the parsed data, and so on.