HIV/STD Risk and PrEP Implementation Messaging Among Gay, Bisexual, and Other Men Who Have Sex With Men

Inclusion Criteria: * Male at birth * Self-identify as Cis-gender Male * Ages 18 or older * ≥1 Male anal sex partner in the 6 months before the baseline screener * Live in or near Atlanta, Chicago, or San Diego * Owns cell phone with data service * Willing to download a health-related app to their cell phone as part of the research study * Willing to participate in a 2-year cohort study with quarterly surveys and HIV and mailed STI self-testing * Able to provide ≥ 2 means of contact * Not currently enrolled in another HIV prevention clinical trial * Not currently living with HIV Exclusion Criteria: * Female at birth * Do not self-identify as Cis-gender Male * Individuals \< 18 years of age * HIV positive status * No male anal sex partner in the 6 months before the baseline interview * Does not own a mobile phone with data service * Not willing to download a health-related app to their cell phone as part of the research study * Live outside the metro Atlanta Metropolitan Statistical Area and/or planning to move from the Atlanta area in the next 2 years * Currently enrolled in an HIV prevention or treatment clinical trial