Extreme metal is a broad term for metal subgenres of a more aggressive style than traditional metal.
This stems back to thrash metal in the 1980s, which mixed influences from punk rock and 1970s heavy metal. Doom metal and its subgenres trace their origins from older styles of metal, though much of what is considered "extreme doom" in modern times is heavily influenced by death and black metal. From thrash metal emerged other forms of extreme metal, such as black metal and death metal. Since this time extreme metal has expanded to cover many fusion, subgenres and other variations.