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 illustrates the wiring for multiple ground fault circuit interrupter receptacles with an unprotected duplex receptacle at the end of the circuit. The load terminals on the gfci are not used and the last receptacle is wired directly to the circuit source.
This page contains wiring diagrams for a ground fault circuit interrupter (gfci) with a built in switch. This device can be used to protect a garbage disposal and provide a gfci protected receptacle in a single gang outlet box. The switch can be included in the protected circuit or it can be used to control an unprotected light or other fixture.
Here 3-wire cable is run from a double-pole circuit breaker and split to supply 120 volts to two sets of receptacles. The neutral wire from the circuit is shared by both. This wiring is commonly used in a 20amp kitchen circuit where two appliance feeds are needed, such as for a refrigerator and a microwave in the same location.