Local councils, the Police, and other authorities (called prosecuting authorities) can issue you an infringement fee for things like speeding, illegal parking or not registering your dog. They send you an Infringement Reminder Notice in the post telling how to pay and how to dispute the infringement if you disagree with it and the due date for payment.
If you don't pay the infringement fee in time, it gets lodged at Court for collection and it becomes a fine. A court cost of $30 is added to the original amount. You get sent a Notice of Fine telling you that the fine has come to Court and you have 28 days to pay the new fine amount to the Court.