According to the US National Institutes of Health, there are four degrees of burn injury, each one progressively more severe than the last.
First Degree: These burns are relatively superficial and only damage the outermost layers of the skin.
Second Degree: This type of burn damages the skin’s outer layer as well as the layers just underneath.
Third Degree: These burns usually require surgical repair due to the significant degree of deep tissue damage.
Fourth Degree: This burn is the most severe. It not only damages skin and underlying tissue, but muscles, tendons, and even bones.