Because they are not hot enough and do not have enough energy in them to heat the skin for long enough to cause a burn. At works the same way as running your finger through the flame of a candle.
It will get hot and possibly burn
Fire is extremaly hot and it can burn of your skin and you could also die. Don't go near fire!
Because synthetic materiel burn vary quickly, burning you and causing the material to melt onto you skin and add additional burn damage.
The sap of some types of Hogweed can burn the skin and cause blisters.
A fire burn consumes your skin as fuel and would keep going until the fuel is gone or it is deprived of oxygen. A steam burn is just water or a liquid that has a lot of thermal energy that it wants to transfer to something that is colder (like your skin). A fire burn would persist, while a steam burn would just get it's thermal energy sapped out and condense into a liquid.
fire
no information
Sparks have a lot of heat which makes them glow. But they do not have temperature. Heat will not cause burns only temperature can. This article might explain why http://www.wereyouwondering.com/what-is-the-difference-between-heat-and-temperature/
if you cut your skin and seep it into your bloodstream then set it on fire. Then yes, it will burn.
Ice cold weather. Acid. Fire.
It will get hot and possibly burn
Both can burn the skin at a certain temprature
You can burn your skin anus and hair and you can set something else on fire.
the electrical bar fire
tan
A burn (caused by radiation, or heat) to the skin.
Yes, acids will burn skin.