Sushi is one of my favorite dishes. I could probably eat it every day if I had the cash flow.
Sushi is a Japanese dish, and can be found almost all over the United States. You can find them in almost any Japanese restaurant and even in Chinese buffets.
Sushi's main ingredient is raw fish or some other type of seafood and rice. There are many different types of fish, resulting in many different types of sushi. The type of sushi also depends on fillings, toppings, condiments, and preparation. There are usually some vegetables and seaweed involved in sushi.
I did not originally know about all the different types, but I came across a cool article describing the different kinds of sushi.
Chirashizushi is a bowl of sushi rice and sashimi (the raw fish in sushi by itself). The bowl usually has raw ingredients and no definite set of ingredients.
Inarizushi is sushi rice filled in a pouch of fried tofu.
Makizushi is rolled sushi. The rolls are formed by using a bamboo mat, and usually rolled using seaweed. There are many different types of Makizushi.
Narezushi is fermented sushi. The main ingredient here is skinned and gutted fish. The fish is placed into a wooden barrel and pickling stone, and can take around six months for it to be ready to eat.
Nigirizushi is hand pressed sushi, where the chef presses sushi rice into small rectangular boxes. The sushi is topped off with wasabi and neta.
Wester-style sushi is a sushi variety that has a western influence. A good example of this is the California roll.
I am not a sushi snob or master by any means, and sometimes I can't even tell the difference between some types of sushi, but I know it is tasty.