The document discusses traction and tractive effort in vehicles. It defines traction as the friction between a drive wheel and the surface it moves upon. Tractive effort is the force available at the contact between drive wheel tires and the road. Traction control systems monitor each wheel and apply braking or torque to wheels that may be slipping to increase traction. Traction can be increased through methods like decreasing tire pressure, tread design, adding tracks/chains, additional weight, and dynamic weight transfer. Non-electric traction systems include steam and internal combustion engine drives, while electric traction uses diesel-electric or gas turbine electric drives.