Final answer:
A burn that results in painful skin and blisters from excessive sunbathing is a second-degree burn, affecting both the epidermis and dermis.
Step-by-step explanation:
When an individual experiences a burn from too much sunbathing that results in skin painful to the touch and small blisters, they have sustained damage to the epidermis and the dermis. These layers comprise the outer and the layer underneath the outer skin respectively. The condition described matches that of a second-degree burn, which affects both the epidermis and extends into the dermis, causing swelling and blistering. Such burns require proper care to prevent infection and could take several weeks to heal.