There are several types of fish sauce, including nam pla from Thailand, nuoc mam from Vietnam and patis from the Phillipines. All are thin brown liquid seasonings rather than side sauces and are based on fermented anchovies.
The flavour and aroma are strong but when tasting, bear in mind that fish sauce should only be used in tiny amounts, and in combination with other ingredients, so that it adds fragrant complexity to the taste, rather than a tongue-lashing.
The term fish sauce generally refers to Eastern varieties, however related sauces do feature in other cuisines, such as Britain's anchovy essence and Worcestershire sauce.
Sprinkle into Eastern-style stocks, soups, stews, stir-fries, noodle dishes and sauces. Combine one part fish sauce with three parts lime juice, plus garlic, chilli and sugar for a delicious dipping sauce to serve with rice-paper rolls, fish cakes and crudités. It can be used at the table in place of salt.