Haring learned to draw from his father, an amateur cartoonist who worked as an engineer in Kutztown, Pennsylvania. The two of them would sit together making pictures. Walt Disney and Charles Schulz were the reference points. That combination of cartoon simplicity and obsessive repetition stayed with him.

He moved to New York in 1978 to attend the School of Visual Arts and within two years had found his medium: white chalk on the matte black paper that covered unused advertising panels in subway stations. He drew in the stations almost every day between 1980 and 1985, sometimes producing forty drawings in a single session. Commuters watched. The police arrested him repeatedly for vandalism. The drawings kept appearing.

The subway work made him famous before galleries did. Radiant babies, barking dogs, crawling figures, flying saucers: a vocabulary of shapes repeated and recombined like a visual language. The line work was fast and confident and looked easy, which was part of the point. He wanted art that anyone could read immediately. In 1986 he opened the Pop Shop in SoHo, selling t-shirts, posters, and badges with his designs at prices people could actually pay. The art world called it selling out. Andy Warhol, who had been doing exactly the same thing for twenty years, supported him.

He was diagnosed with HIV in 1987 and with AIDS the following year. The last works are direct: the 'Ignorance = Fear' poster for ACT UP, the Barcelona mural 'Todos Juntos Podemos Parar el SIDA', the horned sperm figure that became his symbol for the virus. He set up the Keith Haring Foundation in 1989 to fund AIDS organisations and children's programmes. He died in February 1990, at thirty-one. He was cremated and his ashes were scattered in a field near Kutztown, close to where he first sat drawing with his father.