Sushi (1)

In Japanese cuisine, sushi (寿司, 鮨, 鮓, sushi) is vinegared rice, usually topped with other ingredients, including fish, various meats, and vegetables. Outside of Japan, sushi is sometimes misunderstood to mean the raw fish itself, or even any fresh raw-seafood dishes. In Japan, sliced raw fish alone is called sashimi and is distinct from sushi, as sashimi is the raw fish component, not the rice component. The word sushi itself comes from an archaic grammatical form of a word that is no longer used in other contexts; literally, "sushi" means "it's sour".
There are various types of sushi: sushi served rolled inside nori (dried and pressed layer sheets of seaweed or alga) called makizushi (巻き) or rolls; sushi made with toppings laid with hand-formed clumps of rice called nigirizushi (にぎり); toppings stuffed into a small pouch of fried tofu called inarizushi; and toppings served scattered over a bowl of sushi rice called chirashi-zushi (ちらし).

History
The main idea in the preparation of sushi is the preservation and fermentation of fish with salt and rice, a process that has been traced back to Southeast Asia where fish and rice fermentation dishes still exist today. The science behind the fermentation of fish in rice is that the vinegar produced from the fermenting rice breaks the fish down into amino acids. This results in one of the five basic tastes, called umami in Japanese. The oldest form of sushi in Japan, Narezushi still very closely resembles this process. In Japan, Narezushi evolved into Oshizushi and ultimately Edomae nigirizushi, which is what the world today knows as "sushi".
Modern Japanese sushi has little resemblance to the traditional lacto-fermented rice dish. Originally, when the fermented fish was taken out of the rice, only the fish was consumed and the fermented rice was discarded. The strong-tasting and -smelling funazushi, a kind of narezushi made near Lake Biwa in Japan, resembles the traditional fermented dish.
Beginning in the Muromachi period (1336–1573) of Japan, vinegar was added to the mixture for better taste and for preservation. The vinegar accentuated the rice's sourness, and was known to increase its life span, allowing the fermentation process to be shortened and eventually abandoned. In the following centuries, sushi in Osaka evolved into oshi-zushi, the seafood and the rice were pressed using wooden (usually bamboo) molds. By the mid 18th century, this form of sushi had reached Edo (contemporary Tokyo).
Sushi by Hiroshige in Edo periodThe contemporary version, internationally known as "sushi," was invented by Hanaya Yohei (華屋与兵衛; 1799–1858) at the end of Edo period in Edo. The sushi invented by Hanaya was an early form of fast food that was not fermented (it was therefore prepared quickly) and could be eaten with one's hands roadside or in a theatre. Originally, this sushi was known as Edomae zushi, because it used freshly caught fish in the Edo-mae (Edo Bay or Tokyo Bay). Though the fish used in modern sushi no longer usually comes from Tokyo Bay, it is still formally known as Edomae nigirizushi.