Both names refer to a spicy sauce based on fermented fish. Nuoc Mam is the name in Vietnam, Nam Pla in Thailand. The base is fermented small fish, such as anchovies or similar fish, which are fermented naturally in brine. Often spices and chillies are added. The taste thus is generally very spicy and fishy, which many Western people do not like. It is, however, an essential flavouring agent in South-East Asia.