The hot wire to the fan in a fan/light kit will usually be black and the light wire will be blue. The white wire is usually the neutral which is always connected directly to the source neutral, either at the source or through a splice in the switch box. The white wire may also be used to carry current when necessary.
This diagram shows the wiring for multiple receptacles in an arrangement that connects each individually to the source. All wires are spliced to a pigtail which is connected to each device. This wiring allows for voltage at each device independent of the other outlets in the circuit.
This diagram illustrates a switch and receptacle in the same outlet box located in the middle of the circuit. This wiring allows the electricity to continue from the receptacle, on to any other outlets in the circuit and it provides a switch to control a light fixture or other load, such as another receptacle or a fan.
This diagram is similar to the one above, but with the electrical source originating at the fixture. Three-wire cable runs from there to the controllers. The neutral wire from the source is spliced directly to the white wire on the fan/light. The hot source wire is spliced to the white on the 3-wire cable and then spliced to the input wires on both controllers at the other end.