Nuri, also known as KSLV-II, is a three-stage launch vehicle, the second one developed by South Korea and the successor to Naro-1 (KSLV-1). Nuri is developed by Korea Aerospace Research Institute (KARI). All three stages use indigenously developed launch vehicle engines, making Nuri the first indigenously developed South Korean orbital launch vehicle.
KSLV-II Nuri launching from the Launch Pad 2 at Naro Space Center, 21 October 2021.
An artist's render of Nuri's 75-ton-class engine
KRE-075 engine
A multistage rocket or step rocket is a launch vehicle that uses two or more rocket stages, each of which contains its own engines and propellant. A tandem or serial stage is mounted on top of another stage; a parallel stage is attached alongside another stage. The result is effectively two or more rockets stacked on top of or attached next to each other. Two-stage rockets are quite common, but rockets with as many as five separate stages have been successfully launched.
Each stage of the Black Brant 12 sounding rocket has its own set of tail fins.
The second stage of a Minuteman III rocket
Cutaway drawings showing three multi-stage rockets
Apollo 11 Saturn V first-stage separation