Anaerobic organisms are living beings that thrive in environments without oxygen. They obtain energy through processes like fermentation or anaerobic respiration, allowing them to survive in places where oxygen is scarce, such as deep soil, marshes, and the intestines of animals. Common examples include certain bacteria and archaea. These organisms play essential roles in various ecosystems. For instance, they help decompose organic matter, recycling nutrients back into the environment. Additionally, some anaerobic bacteria are used in industrial applications, such as producing biofuels and fermented foods, highlighting their importance in both nature and human activities.