Physical Review X (PRX) is APS’s highly selective, online-only, fully open access journal launched in May 2011. It aims to publish, as timely as possible, a limited number of key papers from all areas of pure, applied, and interdisciplinary physics, that merit broad dissemination and high visibility. PRX’s mission is to disseminate innovative and impactful research advances to the broad science and engineering communities under its open access publishing model.