Anaerobes are microorganisms that thrive in environments without oxygen. They can be found in various habitats, such as deep soil, marshes, and the intestines of animals, including humans. Anaerobes play essential roles in processes like decomposition and nutrient cycling. There are two main types of anaerobes: obligate anaerobes, which cannot survive in the presence of oxygen, and facultative anaerobes, which can grow with or without oxygen. Some anaerobes are beneficial, like those in the human gut that aid digestion, while others can cause infections, such as Clostridium species, which are known for producing toxins.