The candela is the base unit of luminous intensity in the International System of Units (SI). It measures how much light is emitted in a specific direction by a light source. One candela is roughly equivalent to the light produced by a single candle, hence the name. This unit is important in fields like lighting design and photography, as it helps quantify how bright a light source appears to the human eye. The candela is part of a broader system that includes other units like lumen and lux, which measure total light output and illumination, respectively.