Damage to the skin caused by too much exposure to the sun. Ultraviolet rays from the sun burn the skin. Sunburn occurs whenever people engage in outdoor activities without appropriate protection either with clothing and/or sun blocking agents such as suntan lotions. For best prevention one should use a lotion with the highest SPF (sun protection factor). A sunburn can also occur from improper use of tanning beds. A severe sunburn can become sun poisoning which is a potentially life threatening reaction to the damage.