The Japanese term for the vinegared rice used in sushi is shari. It is the seasoned rice that gives sushi its defining sweet-and-sour foundation, whether it is paired with raw fish, cooked seafood, vegetables, or egg.
Shari is prepared from Japanese short-grain rice, whose natural stickiness helps it hold together. The cooked rice is mixed with a dressing usually made from rice vinegar, sugar, and salt; some recipes also include kombu or sake. It is cooled to room temperature before shaping, because hot rice can become overly sticky and damage delicate toppings.
A common mix-up is confusing shari with sushi itself. Sushi refers to the complete dish, while shari means the rice component. Sashimi contains no rice at all, and nori is the dried seaweed sometimes used to wrap rolls. In sushi vocabulary, the fish or other topping placed on the rice is called the neta. The modern nigiri style, in which seafood is placed on hand-pressed shari, is associated with Hanaya Yohei in Edo-period Tokyo around 1824.