Compost is the natural result of of the decay of living matter. Living matter can decay slowly or quickly and it can decay aerobically (in the presence of oxygen) or anaerobically (without oxygen present). Different processes and/or raw materials can create differing compost types. Aerobic decomposition is generally most desirable for soil health and plant growth. Compost is a very commonly used organic/sustainable/biological plant stimulant and fertilizer.