Solid propellant is a type of fuel used in rockets and missiles that is in a solid state. Unlike liquid propellants, which require tanks and pumps, solid propellants are pre-loaded into the rocket and ignite when needed. This makes them simpler and often more reliable for launching spacecraft or military projectiles. The composition of solid propellant typically includes a mixture of fuel and oxidizer, which allows for combustion when ignited. Common examples of solid propellant include those used in Space Shuttle boosters and fireworks. Their design enables efficient thrust generation, making them popular in various aerospace applications.