Communities make an invaluable contribution to the AIDS response. Communities of people living with HIV, of key populations—gay men and other men who have sex with men, people who use drugs, sex workers, transgender people and prisoners—and of women and young people lead and support the delivery of HIV services, defend human rights, support their peers. Communities are the lifeblood of an effective AIDS response and an important pillar of support. World AIDS Day 2019 theme — Communities make the difference