Final answer:
A fourth-degree burn is the highest degree of burn that is characterized by bone involvement and damage to the skin, underlying muscle, and bone. These burns are very severe and can lead to long-lasting complications.
Step-by-step explanation:
A burn can be classified by the degree of severity as first-degree, second-degree, third-degree, or fourth-degree. A fourth-degree burn is the highest degree of burn and is characterized by damage to the skin, underlying muscle, and bone. These burns are very severe and can lead to long-lasting complications. Unlike first and second-degree burns, fourth-degree burns are usually not as painful due to damage to the nerve endings.