UM/UIM is an impotant component of insurance policies. These coverages may protect you and others in the car, when an accident occurs and the other party have no or too little insurance to cover the damage to your car, medical bills and expenses. In simple words, this coverage may protect the driver when an accident occurs and the other party does not have auto insurance. . Some states may require that drivers carry UM/UIM, also known as uninsured/underinsured motorist coverage. For eg. The State of South Dakota currently requires UM/UIM coverage but the State of Washington does not currently requires this coverage.