Blisters are small, fluid-filled sacs that form on the skin's surface, usually as a result of friction, heat, or irritation. They often appear on areas like the hands and feet, especially after activities such as walking or running. When the skin is damaged, the body creates a protective bubble of fluid to cushion the area and promote healing. While blisters can be uncomfortable, they usually heal on their own without medical treatment. It's important to avoid popping them, as this can lead to infection. Keeping the blister clean and covered with a bandage can help protect it while it heals, allowing the skin underneath to recover safely.