The Merriam-Webster Dictionary defines composition as: "the way in which something is put together or arranged : the combination of parts or elements that make up something"
2H2(g) + O2(g) → 2H2O(ℓ) (http://catalog.flatworldknowledge.com/bookhub/2273?e=ball-ch04_s04)
Water is produced from Hydrogen and Oxygen. Although there are two molecules of water being produced, there is only one substance—water—as a product. So this is a composition reaction.
The composition of fireworks
2H2(g) + O2(g) → 2H2O(ℓ) (http://catalog.flatworldknowledge.com/bookhub/2273?e=ball-ch04_s04)
Water is produced from Hydrogen and Oxygen. Although there are two molecules of water being produced, there is only one substance—water—as a product. So this is a composition reaction.
The composition of fireworks