This document provides a basic introduction to rocketry. It explains that rockets work by ejecting pressurized gas through a nozzle, similar to how balloons work when the air inside is released. Rockets use solid or liquid propellants that are burned to produce the pressurized gases, unlike balloons which use compressed air. The document also outlines the main types of rockets and stages of rocket flight, and explains how rockets are able to move according to Newton's third law of motion.