The words "tom yum" are from two Tai words: "tom" and "yam". "Tom" refers to boiling process, while "yam" refers to a kind of Lao and Thai spicy and sour salad. Thus, "tom yum" is a Lao and Thai hot and sour soup. Indeed, tom yum is famous for its distinct hot and sour flavours, with fragrant spices and herbs put together. The basic soup is made of stock and fresh ingredients: lemongrass, kaffir lime leaves, galangal, lime juice, fish sauce, and crushed chili peppers.