Very deep burns are the most life-threatening of all and may require amputation. Types of burns include: First-degree burns damage the outer layer (epidermis) of the skin. These burns usually heal on their own within a week. A common example is a sunburn. Second-degree burns damage not only the outer layer but also the layer beneath it (dermis).
https://www.nigms.nih.gov/education/fact-sheets/Pages/burns.aspx

