Doenjang is a fermented Korean soybean paste with a salty, earthy flavor. It seasons stews, soups and vegetables and is one component of ssamjang. Texture and flavor vary with ingredients and fermentation.
It is distinct from Japanese miso, Chinese bean pastes and chili-based gochujang. Those may work as adaptations in some recipes but are not identical substitutes. Check commercial labels for added grains and other ingredients.
Reference: Further reading.