The chassis number (VIN) is 17 characters long. It never uses the letters I, O and Q, to avoid any confusion with 1 and 0. You will find it in three places:
On the registration document
On the front of the certificate, on the line marked “box E”.
At the bottom of the windscreen
Driver’s side, readable from outside on a small plate.
On the door pillar
Driver’s door open, on the manufacturer’s label.