A CDL endorsement is an additional certification that allows a commercial driver to operate specific types of vehicles or transport certain types of cargo. To obtain an endorsement, drivers must pass written and sometimes driving tests that demonstrate their knowledge and skills related to the specific requirements of the endorsement. There are several types of endorsements, including those for driving tanker vehicles, passenger buses, or transporting hazardous materials. Each endorsement has its own set of regulations and safety standards that drivers must adhere to, ensuring they are qualified to handle the unique challenges associated with those vehicles or cargo types.