Sunblock, also known as sunscreen, is a topical product designed to protect the skin from the harmful effects of ultraviolet (UV) radiation from the sun. It works by either absorbing or reflecting these rays, helping to prevent sunburn and reduce the risk of skin cancer. Sunblock is available in various forms, including lotions, creams, sprays, and sticks, and is often labeled with a Sun Protection Factor (SPF) rating that indicates its effectiveness. To use sunblock effectively, it should be applied generously to all exposed skin at least 15 minutes before sun exposure. It is important to reapply every two hours, or more frequently if swimming or sweating. Choosing a broad-spectrum sunblock protects against both UVA and UVB rays, making it an essential part of sun safety, especially during outdoor activities or in sunny climates.