A candela is a unit of measurement for luminous intensity, which describes how much light a source emits in a specific direction. It is one of the seven base units in the International System of Units (SI) and is symbolized by "cd." The candela is defined based on the light emitted by a source that radiates monochromatic light at a frequency of 540 terahertz and has a radiant intensity of 1/683 watt per steradian. The candela is important in various fields, including lighting design, photometry, and optics. It helps in comparing the brightness of different light sources, such as LEDs and incandescent bulbs. Understanding candelas allows consumers to make informed choices about lighting products based on their brightness and energy efficiency.