Fireworks are not just bursts of light and color in the sky; they are the result of centuries of experience, weeks of planning, and hours of labor. A typical aerial display shell consists of breaks, time-delay fuses, stars, black powder, launch tubes, and a main fuse. The breaks contain stars and bursting charges, which spread decorations over a wide area of the sky. The time-delay fuse ignites the black powder in each break, creating colorful flashes. Stars are the precious cargo of fireworks, and they are carefully made by mixing ingredients and drying them. Black powder, a basic material in fireworks, has a fixed recipe that dates back to 1,000 years ago. Fireworks are launched from steel tubes secured in sand troughs, and a main fuse is used to ignite a lift charge that propels the firework into the air. Overall, creating fireworks involves precision, safety precautions, and careful calculation.
https://www.pbs.org/wgbh/nova/fireworks/anat_nf.html