Sushi is a Japanese dish made from vinegared rice combined with ingredients such as seafood and vegetables.
The defining ingredient is the seasoned rice, called sushi rice or sumeshi—not necessarily raw fish. Sushi may contain raw or cooked seafood, omelette, tofu, cucumber, pickled vegetables, or imitation crab. Vegetarian varieties are also common.
Sushi developed from older Southeast and East Asian fish-preservation techniques in which fish was fermented with rice. The modern style of nigiri sushi is commonly associated with Hanaya Yohei, who is said to have popularised it in Edo, now Tokyo, around 1824. It became a convenient fast food for city residents.
A common mix-up is confusing sushi with sashimi. Sashimi is sliced raw fish or seafood served without vinegared rice, whereas the rice is what defines sushi. Rolls, hand-pressed nigiri, and bowl-style chirashizushi are different forms of the same broader category.