SPF (Sun Protection Factor) is good for the skin because it helps to protect the skin from the harmful ultraviolet (UV) rays of the sun. UV rays can cause damage to the skin, leading to signs of aging such as wrinkles and fine lines, as well as skin cancer. By using products with SPF, you are providing a barrier that filters out UV rays, thus protecting your skin from the sun's harmful effects. It's important to note that sun protection should be part of daily skincare routine, and that it's essential to apply sunscreen with an appropriate SPF regularly and reapply it throughout the day, especially if you are spending a significant amount of time outdoors.