Blood vessel dilation, also known as vasodilation, is the process by which blood vessels widen. This occurs when the smooth muscles in the vessel walls relax, allowing more blood to flow through. Dilation can be triggered by various factors, including increased body temperature, physical activity, or the release of certain chemicals like nitric oxide. This widening of blood vessels helps to lower blood pressure and improve circulation. It plays a crucial role in regulating blood flow to different parts of the body, ensuring that organs and tissues receive adequate oxygen and nutrients during times of increased demand, such as during exercise.