Despite advances in HIV diagnostics, care and prevention strategies, infection rates among adolescent and young adult sexual and gender minorities (SGM) continue to rise in the United States (US). There is an urgent need to describe the epidemiology and trajectories of HIV acquisition in this population and to offer age and culturally appropriate scalable prevention interventions to those at highest risk of infection in the US. This project will engage and retain young SGM in an innovative longitudinal cohort, enroll participants in a dynamic established digital health retention platform (HMP; HealthMPowerment), monitor HIV risk and prevention behaviors and explore the socioecological factors that influence the use of new HIV prevention technologies (UG3 phase), while also allowing targeted testing of novel digital health interventions (UH3 phase). In Aim 1, the investigators will enroll and retain a large (n=6000; 3000/year), diverse cohort of sexually active, SGM adolescents and young adults, ages 13-34, using innovative digital recruitment, engagement and retention strategies. Over the course of the study, the investigators will longitudinally characterize the sexual behavior, HIV transmission risk, and PrEP uptake trajectories of SGM youth utilizing epidemiological trajectory analyses to identify the most effective points of intervention (Aim 2). This study will capitalize upon productive existing partnerships and digital health expertise to articulate the drivers of the ongoing HIV epidemic among the most vulnerable populations in the US in order to identify the most effective, expeditious and scalable strategies to address this ongoing public health crisis.