Generally, all positive wires contain fuses in series in the fusebox to protect the circuits from harm. But, an inline fuse refers to the fuse which has a holder for the fuse fitted into the cable outside of the fusebox. So, an inline fuse is a fuse that is used in the wiring line of the circuit, not in the fusebox. These fuses can be installed anywhere in the circuit. In general, it is best to install the inline fuse near the battery-positive power source. When fusebox space is limited or accessories that aren’t factory-installed or factory designed for circuit protection failed may have an inline fuse. The inline fuses are most commonly used in aftermarket accessories like fog lights, aftermarket door lock unlock actuators, amplifiers, etc.