Nigiri - type of sushi made of thin slices of raw fish on top of pressed rice with vinegar.
Nigiri is usually served in pairs, with a small amount of wasabi between rice and fish, and sometimes with a small amount of nori (algae).
When Japanese say Sashimi, they usually assume it to be "raw fish" Sashimi.
Other varieties of Sashimi are: Chicken Sashimi, Yuba (bean curd) Sashimi, Konnyaku (type of potato) Sashimi.
Sashimi is not always raw fish!