What is Light reflecting off the blood vessels?

Light reflecting off the blood vessels is like when you shine a flashlight on your skin and see tiny red lines, those are blood vessels showing up because they're full of red blood cells.

Imagine your skin is like a window. When light comes in, it can pass through or bounce back. The blood vessels under your skin act like little roads for red cars (the red blood cells) to travel on.

When light hits these roads, the red cars reflect some of that light back up, and that’s why you can see them! It's similar to how a toy car leaves a trail when it zooms across the floor, but instead of paint, it's light being reflected.

If your skin is smooth or thin, like on your face, those red roads are easier to spot. But if you're wearing thick clothes or have lots of layers on, it’s like a fog, the light can't get through as clearly, and those tiny red lines hide from view.

So next time you see a glowing red line on someone's arm, it's just light having fun with blood vessels!