Sushi is the most famous Japanese cuisine in the world but there are several types of sushi.
The most popular ones are nigiri sushi(nigiri zushi) and maki sushi(maki zushi). Nigiri sushi is a sushi with a seafood on the rice and maki sushi is seafood and rice wrapped by seaweed. Seafood can be replaced by vegetable or other ingredients as like egg. However hardly use meat.
Then, the rice has to be flavored with rice vinegar and sugar. Adding the vinegar is for preventing the food poisoning.
Other types of sushi are chirashi sushi(chirashi zushi) and oshi sushi(oshi zushi). Chirasi sushi use similar ingredients but the rice is placed in a bowl and seafood on its top. Then, oshi sushi looks similar to nigiri sushi but it is pressed to be made. Then, the fish is marinated with vinegar too.
Oshi sushi is extremely hard to find at conveyor belt sushi(running sushi) restaurants or authentic sushi bars. Oshi sushi can be found at stores and do not miss the chance to try it when you see it!