Carnet - everything you need to know starts here!
 

There are a LOT of questions on the HUBB about carnets - what are they, how do you use them, WHERE do you use them etc.

Here's links to the information on HU that should help (start here before asking again):

THE primary Paperwork and Carnet info page (on the menu on left, under Trip plan / Paperwork)

List of Countries that DO require a Carnet - Updated regularly - (leads to a link to update-thread)