Aerobic composting requires oxygen, while anaerobic composting takes place in an oxygen-depleted environment.

For example, in English-speaking countries, the term "anaerobic composting" (equivalent to anaerobic decomposition) is used.

T23: anaerobic composting.

Anaerobic digestion or anaerobic composting is the break down of organic materials in the absence of oxygen.

The by-products of anaerobic composting include volatile amines (which smell like rotten fish), hydrogen sulphide (which smells like rotten eggs), and methane.

In North America, "anaerobic composting" is still a common term, but in much of the rest of the world and in technical publications the more accurate term anaerobic digestion is used as the microbes used and the processes involved are quite different.