Load and no-load current of a DC motor
The no-load current is the current required just to turn the motor shaft with nothing connected. It is the current required to overcome the bearing and brush friction plus the aerodynamic drag caused by the rotor moving in the air and moving air through the motor for cooling purposes.

The maximum load current is the maximum continuous current that can be used to continuously drive a load, If the current is higher than that, the motor will run too hot and the insulation will fail eventually. Exceeding the maximum load current slightly will reduce the lifetime of the motor slightly. Exceeding the maximum load current by a lot will cause the motor to fail quickly.

It is also important to understand the locked (or blocked) rotor current. That is the level of current that flows when the motor is not turning. If the motor is started by simply switching it on at full voltage, the locked rotor current flows initially. As the rotor accelerates, the current declines to a lower level. The time that the locked rotor current normally flows is very brief and not harmful to a small motor. To avoid damage, motors rated higher than a few hundred watts require a reduced-voltage starting method to limit the starting current.