A Molotov cocktail , also known as a petrol bomb , bottle bomb , poor man's grenade , Molotovin koktaili (Finnish), polttopullo (Finnish), fire bomb (not to be confused with an actual fire bomb) or just Molotov , is a generic name used for a variety of bottle-based improvised incendiary weapons. Due to the relative ease of production, Molotov cocktails have been used by street criminals, protesters, rioters, gangsters, urban guerrillas, terrorists, irregular soldiers, or even regular soldiers short on equivalent military-issue weapons. They are primarily intended to set targets ablaze rather than obliterate them.
The name "Molotov cocktail" was coined by the Finns during the Winter War,  called in Finnish: Polttopullo or Molotovin koktaili . The name was an insulting reference to Soviet foreign minister Vyacheslav Molotov, who was one of the architects of the Molotov–Ribbentrop Pact signed in late August 1939. The pact with Nazi Germany was widely mocked by the Finns, as was much of the propaganda Molotov produced to accompany the pact, including his declaration on Soviet state radio that bombing missions over Finland were actually airborne humanitarian food deliveries for their starving neighbours. The Finns sarcastically dubbed the Soviet cluster bombs " Molotov bread baskets " in reference to Molotov's propaganda broadcasts. When the hand-held bottle firebomb was developed to attack Soviet tanks, the Finns called it the "Molotov cocktail", as "a drink to go with the food".
A Molotov cocktail is a breakable glass bottle containing a flammable substance such as gasoline, alcohol or a napalm -like mixture, with some motor oil added, and usually a source of ignition such as a burning cloth wick held in place by the bottle's stopper. The wick is usually soaked in alcohol or kerosene, rather than petrol.
In action, the wick is lit and the bottle hurled at a target such as a vehicle or fortification. When the bottle smashes on impact, the ensuing cloud of fuel droplets and vapour is ignited by the attached wick, causing an immediate fireball followed by spreading flames as the remainder of the fuel is consumed.
Other flammable liquids such as diesel fuel, methanol, turpentine, jet fuel, and isopropyl alcohol have been used in place of, or combined with petrol. Thickening agents such as solvents, foam polystyrene, baking soda, petroleum jelly, tar, strips of tyre tubing, nitrocellulose, XPS foam, motor oil, rubber cement, detergent and dish soap have been added to help the burning liquid adhere to the target and create clouds of thick, choking smoke.
Development and use in war
Spanish Civil War
Improvised incendiary devices of this type were used for the first time in the Spanish Civil War between July 1936 and April 1939, before they became known as "Molotov cocktails". In 1936, General Francisco Franco ordered Spanish Nationalist forces to use the weapon against Soviet T-26 tanks supporting the Spanish Republicans in a failed assault on the Nationalist stronghold of Seseña, near Toledo, 40 km (25 mi) south of Madrid. After that, both sides used simple petrol bombs or petrol-soaked blankets with some success. Tom Wintringham, a veteran of the International Brigades, later publicised his recommended method of using them:
We made use of "petrol bombs" roughly as follows: take a 2lb glass jam jar. Fill with petrol. Take a heavy curtain, half a blanket, or some other heavy material. Wrap this over the mouth of the jar, tie it round the neck with string, leave the ends of the material hanging free. When you want to use it have somebody standing by with a light [i.e., a source of ignition]. Put a corner of the material down in front of you, turn the bottle over so that petrol soaks out round the mouth of the bottle and drips on to this corner of the material. Turn the bottle right way up again, hold it in your right hand, most of the blanket bunched beneath the bottle, with your left hand take the blanket near the corner that is wetted with petrol. Wait for your tank. When near enough, your pal [or comrade-in-arms] lights the petrol soaked corner of the blanket. Throw the bottle and blanket as soon as this corner is flaring. (You cannot throw it far.) See that it drops in front of the tank. The blanket should catch in the tracks or in a cog-wheel, or wind itself round an axle. The bottle will smash, but the petrol should soak the blanket well enough to make a really healthy fire which will burn the rubber wheels on which the tank track runs, set fire to the carburetor or frizzle the crew. Do not play with these things. They are highly dangerous.
The Battle of Khalkhin Gol, a border conflict of 1939 ostensibly between Mongolia and Manchukuo, saw heavy fighting between Japanese and Soviet forces. Short of anti-tank equipment, Japanese infantry attacked Soviet tanks with gasoline-filled bottles. Japanese infantrymen claimed that several hundred Soviet tanks had been destroyed this way, though Soviet loss records do not support this assessment.
On 30 November 1939, the Soviet Union attacked Finland, starting what came to be known as the Winter War. The Finns perfected the design and tactical use of the petrol bomb. The fuel for the Molotov cocktail was refined to a slightly sticky mixture of gasoline, kerosene, tar, and potassium chlorate. Further refinements included the attachment of wind-proof matches or a phial of chemicals that would ignite on breakage, thereby removing the need to pre-ignite the bottle, and leaving the bottle about one-third empty was found to make breaking more likely.
A British War Office report dated June 1940 noted that:
The Finns' policy was to allow the Russian tanks to penetrate their defences, even inducing them to do so by 'canalising' them through gaps and concentrating their small arms fire on the infantry following them. The tanks that penetrated were taken on by gun fire in the open and by small parties of men armed with explosive charges and petrol bombs in the forests and villages... The essence of the policy was the separation of the AFVs from the infantry, as once on their own the tank has many blind spots and once brought to a stop can be disposed of at leisure. 
Molotov cocktails were eventually mass-produced by the Alko corporation at its Rajamäki distillery, bundled with matches to light them. Production totalled 450,000 during the Winter War. The original recipe of the Molotov cocktail was a mixture of ethanol, tar and gasoline in a 750 millilitres (0.79 US qt) bottle. The bottle had two long pyrotechnic storm matches attached to either side. Before use, one or both of the matches was lit; when the bottle broke on impact, the mixture ignited. The storm matches were found to be safer to use than a burning rag on the mouth of the bottle.
Early in 1940, with the prospect of immediate invasion, the possibilities of the petrol bomb gripped the imagination of the British public. For the layman, the petrol bomb had the benefit of using entirely familiar and available materials, and they were quickly improvised in large numbers, with the intention of using them against enemy tanks. 
The Finns had found that they were effective when used in the right way and in sufficient numbers. Although the experience of the Spanish Civil War received more publicity, the more sophisticated petroleum warfare tactics of the Finns were not lost on British commanders. In his 5 June address to LDV leaders, General Ironside said:
I want to develop this thing they developed in Finland, called the "Molotov cocktail", a bottle filled with resin, petrol and tar which if thrown on top of a tank will ignite, and if you throw half a dozen or more on it you have them cooked. It is quite an effective thing. If you can use your ingenuity, I give you a picture of a [road] block with two houses close to the block, overlooking it. There are many villages like that. Out of the top windows is the place to drop these things on the tank as it passes the block. It may only stop it for two minutes there, but it will be quite effective.
Wintringham advised that a tank that was isolated from supporting infantry was potentially vulnerable to men who had the required determination and cunning to get close. Rifles or even a shotgun would be sufficient to persuade the crew to close all the hatches, and then the view from the tank is very limited; a turret-mounted machine gun has a very slow traverse and cannot hope to fend off attackers coming from all directions. Once sufficiently close, it is possible to hide where the tank's gunner cannot see: "The most dangerous distance away from a tank is 200 yards; the safest distance is six inches." Petrol bombs will soon produce a pall of blinding smoke, and a well-placed explosive package or even a stout iron bar in the tracks can immobilise the vehicle, leaving it at the mercy of further petrol bombs – which will suffocate the engine and possibly the crew – or an explosive charge or anti-tank mine.
By August 1940, the War Office produced training instructions for the creation and use of Molotov cocktails. The instructions suggested scoring the bottles vertically with a diamond to ensure breakage and providing fuel-soaked rag, windproof matches or a length of cinema film (made of highly flammable nitrocellulose) as a source of ignition.
On 29 July 1940, manufacturers Albright & Wilson of Oldbury demonstrated to the RAF how their white phosphorus could be used to ignite incendiary bombs. The demonstration involved throwing glass bottles containing a mixture of petrol and phosphorus at pieces of wood and into a hut. On breaking, the phosphorus was exposed to the air and spontaneously ignited; the petrol also burned, resulting in a fierce fire. Because of safety concerns, the RAF was not interested in white phosphorus as a source of ignition, but the idea of a self-igniting petrol bomb took hold. Initially known as an A.W. bomb, it was officially named the No. 76 Grenade, but more commonly known as the SIP (Self-Igniting Phosphorus) grenade. The perfected list of ingredients was white phosphorus, benzene, water and a two-inch strip of raw rubber ; all in a half-pint bottle sealed with a crown stopper. Over time, the rubber would slowly dissolve, making the contents slightly sticky, and the mixture would separate into two layers – this was intentional, and the grenade should not be shaken to mix the layers, as this would only delay ignition. When thrown against a hard surface, the glass would shatter and the contents would instantly ignite, liberating choking fumes of phosphorus pentoxide and sulfur dioxide as well as producing a great deal of heat. Strict instructions were issued to store the grenades safely, preferably underwater and certainly never in a house. Mainly issued to the Home Guard as an anti-tank weapon, it was produced in vast numbers; by August 1941 well over 6,000,000 had been manufactured. 
There were many who were sceptical about the efficacy of Molotov cocktails and SIPs grenades against the more modern German tanks. Weapon designer Stuart Macrae witnessed a trial of the SIPs grenade at Farnborough: "There was some concern that, if the tank drivers could not pull up quickly enough and hop out, they were likely to be frizzled to death, but after looking at the bottles they said they would be happy to take a chance." The drivers were proved right, trials on modern British tanks confirmed that Molotov and SIP grenades caused the occupants of the tanks "no inconvenience whatsoever".
Wintringham, though enthusiastic about improvised weapons, cautioned against a reliance on petrol bombs and repeatedly emphasised the importance of using explosive charges.
During the Irish War of Independence, the Irish Republican Army sometimes used sods of turf soaked in paraffin oil to attack British army barracks. Fencing wire was pushed through the sod to make a throwing handle.
The Polish Home Army developed a version  which ignited on impact without the need of a wick. Ignition was caused by a reaction between concentrated sulfuric acid mixed with the fuel and a mixture of potassium chlorate and sugar which was crystallized from solution onto a rag attached to the bottle.
During the Second Battle of Fallujah in 2004, U.S. Marines employed Molotov cocktails made with "one part liquid laundry detergent, two parts gas" for 'burning out' their enemies from houses.
Molotov cocktails were also used by protesters and civilian militia in Ukraine during violent outbreaks of the Euromaidan and the 2014 Ukrainian revolution. Protesters during the Ferguson riots used Molotov cocktails. 
In Bangladesh during anti government protests before the 2014 national election and in the year afterwards, many buses and cars were targeted with petrol bombs. A number of people burnt to death and many more were injured.  
During the protests in Venezuela from 2014 and into 2017, protesters had used Molotov cocktails similar demonstrators in other countries.  As the 2017 Venezuelan protests intensified, demonstrators began using "Puputovs", a play on words of Molotov, with glass devices filled with excrement being thrown at authorities after the PSUV ruling-party official, Jacqueline Faría, mocked protesters who had to crawl through sewage in Caracas' Guaire River to avoid tear gas.   On 8 May, the hashtag #puputov became the top trend on Twitter in Venezuela as reports of authorities vomiting after being drenched in excrement began to circulate.   By 10 May 2017, Venezuelans unrelated to political parties called for a "Marcha de la Mierda", or a "March of Shit" , essentially establishing puputovs in the arsenal of Venezuelan protesters.   A month later on 4 June 2017 during protests against Donald Trump in Portland, Oregon, protesters began throwing balloons filled with "unknown, foul-smelling liquid" at officers. 
As incendiary devices, Molotov cocktails are illegal to manufacture or possess in many regions. In the United States, Molotov cocktails are considered " destructive devices " under the National Firearms Act and regulated by the ATF.