The stop sign is a sign which is often met at crossroads, when a road does not have traffic lights. This sign instruct the drivers to stop when they reach the crossroad. They can only proceed when the road ahead is empty. Otherwise they must wait for the other vehicles to pass. When the other vehicle have passed, the driver can proceed. This sign is one of the most significant and known signs of road traffic.
The stop sign is not common in every country. In some countries the stop sign is also written in the local language for example in Quebec (Canada), Japan etc. Some decades ago a different symbol was used to indicate the stop sign.