In this wiring, the source is at the switch and 3-wire cable runs from there to the fan/light. The switch controls the light and the source is spliced through to the fan. With this arrangement, the fan is controlled by a pull-chain on the motor housing and the light is controlled with the switch. The neutral and ground wires are also spliced through to the fan/light.
The black wire is splice to the output on the speed controller and to the black, fan wire at the other end. The red wire is spliced to the output on the dimmer and to the blue, light wire at the other end. The neutral from the source is spliced in the switch box with the white wire, and to the neutral wire on the ceiling fixture at the other end.
In this arrangement with 2 switches in one box, the bottom terminals are connected to pigtails spliced to the source. The top switch terminals connect to the black wires running to the light fixtures. The source neutral and ground wires are spliced to run to each light box.
This diagram illustrates wiring a GFCI receptacle and light switch in the same outlet box, a common arrangement in a bathroom with limited space. The hot source is spliced to the LINE terminal on the receptacle and to the bottom terminal on the light switch. The neutral and ground wires are spliced together and run to each device in the circuit.