In the case of a small car accident
If a small car accident, such as bumping into another car, you should both go to the side of the road and discuss the situation. Let's say that person A's car bumped into person B's car. They should both take down the other car's license plate and ther other person's name, phone number and address. Person A is responsible for getting Person B's insurance information, so that Person A can contact his/her respective insurance to let them know about the accident. Person B's insurance company will then charge Person A's insurance company for the damages and consequences.
If the accident is more serious, you should call the police (110).