This study aims to understand how men who have sex with men (MSM) prevent HIV and sexually transmitted infections (STIs). HIV is a virus that attacks the immune system, and STIs are infections passed from one person to another through sexual contact. The study will focus on learning about the use of PrEP (Pre-exposure Prophylaxis), a medicine taken to prevent HIV, and other prevention strategies like using condoms. Participants will be from Atlanta, Chicago, and San Diego and will include men who identify as gay, bisexual, or have sex with other men. The study will last two years, with participants completing surveys every three months and HIV/STI testing every six months.

• The study lasts for 2 years with regular surveys and tests.
• Participants need to use a health app on their phone.
• Must not be in another HIV prevention trial or have HIV.