HTML hidden variable?

[tabariz]

Can anybody explain to me what this part of code actually means?
<FORM ACTION="http://www.yellowpages.com.jo/pj.pl" METHOD="POST" NAME="mainform">
<INPUT TYPE="HIDDEN" NAME="T" VALUE="PJ">
<INPUT TYPE="HIDDEN" NAME="L" VALUE="en">
<INPUT TYPE="HIDDEN" NAME="OP" VALUE="PJ2">
<INPUT TYPE="HIDDEN" NAME="OFF" VALUE="0">

[boogyman]

it is a form to submit some type of hidden information to the url by the POST method
http://www.yellowpages.com.jo/pj.pl

(POST VARIABLE) T VALUE PJ
(POST VARIABLE) L VALUE en
(POST VARIABLE) OP VALUE PJ2
(POST VARIABLE) OFF VALUE 0

[djr33]

Hidden information is no different in a form than any other field, except in how it is displayed. (Well, at least compared to the type "text".)

For example, the "password" type field does nothing to the data, but just makes it ***** instead of text, when typing. So, the type is just to tell the browser what to do with it. The hidden type is not displayed on the page and acts as extra information sent on by form to the next page, like maybe your current score, or something. It's not secure, though, because it can be viewed in the source and manipulated by Javascript.