What are class AB and C vehicles?

CDL Classes Commercial B: Any single vehicle with a GVWR of more than 26,000 pounds, any such vehicle towing a vehicle not in excess of 10,000 pounds GVWR, or a 3-axle vehicle weighing over 6,000 pounds. Commercial C: Any Class C vehicle with one or more of the following endorsements: Hazardous Materials (HazMat)