Black Flag are primarily a hardcore punk band and are considered to be one of the first hardcore punk bands. According to Ryan Cooper of About.com and author Doyle Greene, Black Flag is one of the pioneers of the genre for the experimental style they later started playing. Black Flag experimented with a sludge metal sound on their album "My War". Black Flag also have used elements of styles such as jazz, blues, spoken word, heavy metal, blues rock, free jazz, math rock and .