Solid propulsion refers to a type of rocket propulsion that uses solid propellant to generate thrust. The propellant is a mixture of fuel and oxidizer that is preloaded into the rocket motor. When ignited, the solid propellant burns uniformly, producing hot gases that are expelled through a nozzle, propelling the rocket forward. This method of propulsion is commonly used in various applications, including spacecraft, missiles, and fireworks. Solid propulsion systems are known for their simplicity, reliability, and ease of storage, making them a popular choice for many aerospace and defense projects.