When a fair skinned person blushes why does their skin turn red?

When a fair-skinned person blushes, their skin turns red due to increased blood flow to the superficial blood vessels in the face. This dilation of blood vessels, known as vasodilation, occurs in response to emotional stimuli, like embarrassment or excitement. The lighter pigmentation of fair skin allows the underlying red blood to become more visible, resulting in the characteristic reddening of the cheeks.