There are 3 doors,behind which are two goats and a car
You pick a door (call it door A). You are hoping for a car
Then,the game host,examines the other doors (B&C) and always opens one of them with a goat (if both doors have goats,he will randomly pick one to open)
Do you stick with door A (original guess) or switch to the other unopened door? Does it matter?