Burns are classified by how deeply they damage the skin. First-degree burns affect only the outer layer (epidermis) and cause redness and pain, like a mild sunburn. Second-degree burns go deeper into the dermis, causing blisters, swelling, and more pain. Third-degree burns damage all layers of the skin and may appear white, charred, or numb due to nerve damage, and need urgent medical care. The skin has three main layers: epidermis (outer), dermis (middle), and subcutaneous layer (inner), and it plays a vital role in protecting the body from infection, regulating temperature, preventing water loss, and sensing touch, pain, and heat.