Underneath your skin they look like thin blue lines
The scientific name for veins that are close to the surface is superficial veins. These are the veins you can see under your skin.
When you look underneath your tongue, you can see purple veins. So yes, there are veins in the tongue.
no
You could see his veins popping out from his skin.
Look at the back of your hand. Do you see some branch-like blue things showing? Those are your veins.
See a doctor.
You will need a dermatologist for varicose veins. Your regular Doctor can refer you to a specialist.
Temperature has little, if anything to do with vein visibility. You can see veins at any given time (usually), if you look at your wrist or anyplace the skin is thin.
Veins are invisible when the skin is cold while if the skin is warm you can easily see it or it pops out.
Ofcourse not, you don't see them, your fingernails can't bleed and the body doesn't see a need to put nerves in it.
Because you are light skined
Your veins.