A truck carries cargo, not people. That is the defining purpose. Everything else, cab size, engine type, number of axles, follows from what the truck is built to haul.

The category spans a huge range. A light pickup carries a half-ton. A semi-tractor pulls 40 tons of trailer. Dump trucks, box trucks, flatbeds, tankers, and refrigerated units all serve specific freight needs. Most goods in a modern economy spend time on a truck at some point.

Truck classes by weight

• Class 1-3: light duty, pickups and vans.
• Class 4-6: medium duty, box trucks and city delivery.
• Class 7-8: heavy duty, semi-tractors and dump trucks.
• Commercial driver's license required above certain weights.

Trucking moves the majority of freight in the United States by value and weight. Diesel dominates heavy-duty applications because of its torque and efficiency. Electric trucks are entering short-haul and drayage routes, where predictable mileage and depot charging work well. Long-haul electric trucking remains limited by battery weight and charging infrastructure. The truck is unglamorous, but supply chains run on it.