The term 4th order refers to the fourth level of FIREWORKS, which is the highest level of FIREWORKS. FIREWORKS is a type of pyrotechnic display that is used for entertainment and celebration. It typically consists of the combustion of gunpowder or other combustible materials, producing a colorful display of light and sound. The 4th order of FIREWORKS is the most powerful and impressive, and is usually used for special occasions such as weddings, festivals, and national holidays.