Phenylbenzimidazole sulfonic acid (PBSA), also known as ensulizole, is an organic compound widely used in sunscreens and cosmetic products as a UV filter. It primarily provides protection against UVB rays, helping to prevent sunburn and skin damage caused by sun exposure. Due to its water-soluble nature and light texture, it is especially favored in formulations for daily wear, offering effective sun protection without a greasy feel.