Methanogens are a group of microorganisms that produce methane as a byproduct of their metabolic processes. They belong to the domain of Archaea, which are single-celled organisms distinct from bacteria. Methanogens thrive in anaerobic environments, such as swamps, marshes, and the digestive tracts of ruminants like cows, where they play a crucial role in breaking down organic matter. These microorganisms are essential for the global carbon cycle, as they help decompose organic materials and release methane, a potent greenhouse gas. Methanogens are also studied for their potential in biogas production, which can be harnessed as a renewable energy source.