Brightness refers to the perception of how much light an object emits, reflects, or transmits. It is a key aspect of visual perception and is measured in units like lumens or candelas. Brightness can vary based on the intensity of the light source and the distance from the observer. In everyday life, brightness affects how we see colors and shapes. For example, a bright sun can make colors appear more vivid, while a dimly lit room may cause colors to look muted. Understanding brightness is important in fields like photography, where proper lighting can enhance the quality of images.