[thelist] Hidden Fields

[kev.skindrill]

... i also pass the data as hidden fields so if there's a
> bad connection or the user walks away for a few he/she can pick
> right up (since a session might expire in the meantime, but hidden
> fields won't

I have often seen references to hidden fields & I'm ashamed to admit I
haven't got a clue what they are about or their uses. Could someone possibly
point me in the direction of any good tutorials about them please. And
thanks for the answer about the "pl" extension.

K