Ultraviolet A and Ultraviolet B refer to the harmful rays from the sun. Overexposure to either can lead to skin cancer. Here is a breakdown of the two from the American Academy of Dermatology:
• UVA rays (or aging rays) can prematurely age your skin, causing wrinkles and age spots, and can pass through window glass.
• UVB rays (or burning rays) are the primary cause of sunburn and are blocked by window glass.