Wearing sunscreen is one of the best — and easiest — ways to protect your skin’s appearance and health at any age. Used regularly, sunscreen helps prevent sunburn, skin cancer and premature aging. To help make sunscreen a part of your daily routine, dermatologist Anna Chien addresses common concerns. What is SPF? Sun protection factor (SPF) represents a sunscreen’s ability to protect against a specific portion of ultraviolet (UV) light called UVB. UVB rays are responsible for sunburns and skin cancer. There are two other portions of UV light: UVC rays (which don’t pass the earth’s atmosphere) and UVA rays (which are also responsible for skin cancer as well as skin aging). A sunscreen that is broad spectrum will protect against both UVB and UVA rays. What sunscreen should I buy? For day-to-day use, pick a sunscreen with an SPF of at least 30. If you spend time outdoors, choose a product with SPF 60 or greater. In reality, most people do not use as much sunscreen as they should, and this higher SPF helps compensate for the reduced application.