Sushi is rice rolls with vegetables and fish. The rolls are usually seasoned with soy sauce and wasabi. They can be garnished with meat from short, thin strips of cooked shrimp, cooked crab legs, raw salmon or tuna. Sushi is a typical food of Japan, China and all of Asia. Today there are sushi restaurants all over the world. Sushi was first mentioned in a Chinese dictionary from the 2nd century. It is assumed that this dish appeared somewhere in China and Southeast Asia, and only in the VII-VIII century was it brought to Japan. Sushi was originally not a food, but a simple, ancient practice of preserving salted fish with rice. The traditional ``sushi'' process invented in Southeast Asia is a popular method of preserving fish throughout the region to this day. The word sushi is an obsolete grammatical form that is no longer used in its original context and serves only to indicate the dish. The scientific explanation for the fermentation of fish rolled in rice is that the vinegar from the fermenting rice breaks down the fish into amino acids. Modern Japanese sushi has almost nothing in common with the traditional fermented rice dish. Originally, after the fermented fish was removed from the rice, only the meat was eaten and the rice was thrown away. There are hundreds of types of sushi, but a few basic types are the most popular. Sushi that is served on discs wrapped in pressed dried seaweed (nori sheets) is called maki-sushi. Stuffing in a pocket of fried tofu is called inari-sushi. A bowl of sushi rice topped with seafood is called chirashi-sushi. The oval balls of rice with seafood on top are called nigiri-sushi.