Burns are injuries to the skin and underlying tissues caused by heat, chemicals, electricity, radiation, or friction, resulting in damage that can range from mild redness to deep tissue destruction. They are classified by severity: first-degree burns affect only the outer layer of skin, second-degree burns involve deeper layers and often cause blisters, and third-degree burns extend through the full thickness of the skin and may damage nerves and underlying structures. Symptoms may include pain, swelling, blistering, charring, or numbness in severe cases. Minor burns can often be treated with cooling, clean dressings, and pain management, while more serious burns require immediate medical attention to prevent infection, fluid loss, and other life-threatening complications.