A Molotov cocktail (among several other names – see other names) is a hand-thrown incendiary weapon constructed from a frangible container filled with flammable substances equipped with a fuse (typically a glass bottle filled with flammable liquids sealed with a cloth wick). In use, the fuse attached to the container is lit and the weapon is thrown, shattering on impact. This ignites the flammable substances contained in the bottle and spreads flames as the fuel burns.

Due to their relative ease of production, Molotov cocktails are typically improvised weapons. Their improvised usage spans from criminals, rioters, football hooligans, urban guerrillas, terrorists, irregular soldiers, freedom fighters, and even regular soldiers, in the latter case often due to a shortage of equivalent military-issued weapons. Despite its improvised and rebellious nature, many modern militaries exercise the use of Molotov cocktails.

However, Molotov cocktails are not always improvised in the field. It is not uncommon for them to be mass-produced to a certain standard as part of preparation for combat. Some examples of this being done are the anti-invasion preparations of the British Home Guard during WWII and the Ukrainian volunteer units during the 2022 Russian invasion of Ukraine. During World War II, Molotov cocktails were even factory produced in several countries, such as: Finland, Nazi Germany, the Soviet Union, Sweden and the United States, some featuring specially designed frangible containers and fuses (such as the US Frangible Grenade M1 for example).