Brightness is the quality of giving off or reflecting a lot of light. A sunny day has more brightness than a cloudy one. A freshly polished mirror has more brightness than a dusty window. When you turn up the brightness on your tablet screen, you're making it emit more light so it's easier to see.

The word also describes how light or dark a color appears. A bright yellow catches your eye immediately, while a dull yellow fades into the background. Artists adjust the brightness of their paints to create depth and emphasis in their paintings.

Beyond light, brightness can describe someone's mental sharpness or intelligence. When we say a student shows brightness, we mean they learn quickly and think clearly. Their mind seems to shine with understanding, just like a lamp shines with light.

Scientists measure brightness precisely using instruments, but we experience it intuitively every day. The brightness of a campfire creates a cozy circle of light in the darkness. The brightness of snow on a sunny day can actually hurt your eyes. That quality of radiating or reflecting light intensely, whether from the sun, a lightbulb, or even someone's smile, is what brightness captures.