First aid and self-care information for burns. A burn is an injury to the skin resulting from direct contact or exposure from extreme heat or cold, friction, electricity, or chemicals. First-degree burns are superficial with red skin, pain, and no blistering. Second-degree burns involve destruction of the second layer of skin, causing blistering, swelling, and pain. Third-degree burns involve destruction of all layers of the skin, including fat, muscle, blood supply, and sometimes bone.