The word "rocket" may refer to a couple of different objects. A rocket can be a type of flying vehicle used by astronauts, space explorers, and even unmanned space flights. A rocket can also be a weapon, fired by anything from tanks to airplanes. A model rocket is a small toy used by hobbyists to propel fireworks or to practice direct air launching.

No matter the type of rocket, there is always a propellant or chemical reaction used to set off the rocket in motion. This propellant can be gasoline or more complex mixes such as liquid oxygen and liquid hydrogen. Sometimes a rocket uses other propulsion systems to get into the air. A rocket is the main propellant of spacecrafts. Without it, it would be impossible for artificial satellites, spacecrafts, and other interplanetary vehicles to reach enough of a thrust to leave Earth, reach space, and then establish a flight pattern.

The difference between the rocket used as a weapon and the rocket used in spacecrafts is mainly in the construction. Spacecraft rockets have a strong but short thrust, as their only function is to get the vehicle into space; once there, the rockets are then separated from the main body and abandoned into space. Weapon rockets, on the other hand, need to maintain a long trajectory, so staying power is more important than explosive power.

The earliest form of a rocket was used for firework displays in China and India. There are written accounts of the Han Dynasty using rockets as far back as 206 BC, but it wasn't until 1379 AD that the Italians developed an early form of a firecracker. From then on, all rockets created were designed with either weaponry or display in mind.

Russian mathematician Konstantin Tsiolkovsky was the first to suggest the use of rockets for space travel. Tsiolkovsky was a visionary who had his eyes on space as early as 1903. By the mid-1920s, Germany had taken a serious interest in rocket science, where they took the leading spot in research and use of rockets.