To glow is to shine with light. On a clear night when the moon is full, it glows in the sky.
A nightlight glows in a dark room, and a distant flashlight beam glows like a candle. Other things that glow include fireflies, TV screens, and city lights when seen from an airplane at night. A person's face can also be said to glow, when it's shining and flushed with health or happiness. The radiance of light or pleasure itself can also be called a glow, from the Old English glowan, "to shine as if red-hot."