How rockets work

During the Sung Dynasty (960-1279), the Chinese invented the first type of rockets: the firework. According to legend a cook discovered that a perfect mixture of sulfur, saltpeter, and charcoal (gunpowder) was extremely flammable and would explode, if enclosed in a small space; which is why in fireworks, gunpowder is enclosed in tubes. The Chinese soon discovered that this black powder could shoot up into the sky at tremendous speeds. That marked the beginning of rocket technology. Gunpowder was developed and commercialized by skilled tradesmen, who also made fireworks for entertainment.

Although the Chinese invented the first rockets, the powerful rockets used today have their direct origins the United States and Europe. Robert Goddard demonstrated a liquid fuel rocket capable of reaching high altitudes. This was followed by advancements from Russian and German scientists creating rocket weapons before World War II.
The mixture that provides the Solid Rocket Boosters with fuel.

Rockets are usually powered by a chemical reaction or explosion within the rocket itself. Rockets can be powered by different types of fuel: early Chinese rockets used gunpowder, later on people used gasoline and other petroleum products to fuel rockets. Rocket fuels often had to be kept frozen to avoid explosions. Some rockets combine hydrogen and oxygen to create an intense chemical reaction. Some, such as the Russian N1, use kerosene. The Saturn V had 3 stages and used both petroleum fuel (in the first stage) and hydrogen fuel (in the second and third stages).