https://www.grc.nasa.gov/www/k-12/airplane/lrockth.html

1. Liquid rocket fuel.
2. Oxidizer.
3. Pumps carry the fuel and oxidizer.
4. The combustion chamber mixes and burns the two liquids.
5. The hot exhaust is choked at the throat, which, among other things, dictates the amount of thrust produced.
6. Exhaust exits the rocket.