{Reference Type}: Journal Article {Title}: Sunscreens Part 1: Mechanisms and Efficacy. {Author}: Azim SA;Bainvoll L;Vecerek N;DeLeo VA;Adler BL; {Journal}: J Am Acad Dermatol {Volume}: 0 {Issue}: 0 {Year}: 2024 May 19 {Factor}: 15.487 {DOI}: 10.1016/j.jaad.2024.02.065 {Abstract}: As our knowledge of the harmful effects of ultraviolet radiation continues to evolve, sunscreen remains an integral part of a comprehensive photoprotection strategy against multiple endpoints of ultraviolet-mediated damage. Part 1 of this review covers sunscreen active and additive ingredient properties, mechanisms of action and gaps in coverage. Following an overview of sunscreen's efficacy in protecting against sunburn, photocarcinogenesis, photoaging, pigmentary disorders, and idiopathic photodermatoses, we highlight considerations for product use and selection in children and individuals with skin of color.