Dimming allows for change in the ambiance of a space by altering the light level. Using only the light level needed at a particular time saves energy, but the energy savings from dimming are relatively small compared with the possible energy savings from switching from incandescent bulbs to CFLs or LEDs. If lower light outputs are consistently desired, consider using lower wattage or fewer bulbs instead of a dimmer.
Wall-mounted dimmers are available in many styles such as toggle, rotary, linear slide, and touch. Toggle dimmers look like a toggle switch and provide full-range dimming control. Rotary dimmers use a knob to adjust light output: push the knob to turn on/off, or turn the knob to alter light output. Linear slide dimmers provide dimming using an up/down slide element to adjust the lighting, and some have programmable "preset" buttons. Touch dimmers provide dimming control using a touch-sensitive panel. Bi-level dimmers are combined with a sensor to dim bulbs to a preset level when no motion is detected in a space, and some have programmable "preset" buttons. Socket and cord dimmers are used for plug-in table or floor fixtures that are not manufactured with a dimming switch.
Dimming incandescent bulbs, including halogen, decreases the light output, decreases energy use, and extends the life of the bulb. Dimming fluorescent lamps decreases light output and energy use, but does not extend life. Dimming LEDs may extend life.