A hybrid rocket is a type of rocket that uses a combination of solid and liquid propellants. The solid propellant is typically a rubber-like material, while the liquid oxidizer, such as nitrous oxide, is injected into the combustion chamber. This design allows for better control of thrust and can be more efficient than traditional solid rockets. Hybrid rockets are often considered safer than fully liquid or solid rockets because they can be shut down more easily. They are used in various applications, including space exploration and commercial launches, and are being developed by companies like SpaceX and Virgin Galactic.