Metalcore is a fusion genre that combines elements of heavy metal and hardcore punk. It typically features aggressive guitar riffs, breakdowns, and a mix of clean and screamed vocals. The genre emerged in the late 1980s and gained popularity in the early 2000s, with bands like Killswitch Engage and August Burns Red leading the way. The music often addresses themes of personal struggle, social issues, and emotional experiences. Metalcore is known for its energetic live performances and has influenced various subgenres, including post-hardcore and melodic metalcore. Its diverse sound appeals to a wide range of listeners.