In Japanese cuisine, 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 The word sushi itself comes from an outdated grammatical form of a word that is no longer used in other contexts; literally, sushi means “it’s sour.”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 or rolls; sushi made with toppings laid with hand-formed clumps of rice called nigirizushi; toppings stuffed into a small pouch of fried tofu called inarizushi; and toppings served scattered over a bowl of sushi rice called chirashi-zushi.
[ Source: Wikipedia ]
Cristóbal Vila, June 2008, Zaragoza, Spain