What is drone doom?

Drone doom is a subgenre of doom metal that focuses heavily on repetitive, sustained drones and low-frequency tones. It is characterized by slow tempos, heavy distortion, and minimalistic song structures. Vocals are usually sparse and often harsh in nature, with lyrics often dealing with themes such as nihilism, depression, and despair. The use of drones and feedback is often used to create an eerie, otherworldly atmosphere. Notable bands in the genre include Sunn O))), Earth, and Boris.