The gas van or gas wagon (German: Gaswagen; Russian: душегубка; Serbian: душегупка) was an extermination method devised by Nazi Germany to kill victims of the regime. It was also rumored that an analog of such a device was used by the Soviet Union on an experimental basis during the Great Purge.

During trips to Russia in 1941, Heinrich Himmler learned the psychological impact on the Einsatzgruppen killers posed by the shooting of women and children. Hence, he commissioned Arthur Nebe to explore ways of killing that were less stressful for the killers. Nebe's experiments eventually led to the production of the gas van. This vehicle had already been used in 1940 for the gassing of East Prussian Pomeranian mental patients in Soldau, a camp located in the former Polish corridor. One application by the Nazis gas van became known in 1943 after the trial of members of crimes against humanity committed in the territory of the Krasnodar Territory of the USSR, where about 7,000 civilians were killed by gas poisoning. It was a vehicle with an airtight compartment for victims, into which exhaust gas was piped while the engine was running. As a result, the victims were gassed with carbon monoxide, resulting in death by the combined effects of carbon monoxide poisoning and suffocation. The suffocations usually occurred as the gas van was carrying the victims to a freshly dug pit or ravine for mass burial.

Gas is one of the three classical states of matter (the others being liquid and solid). Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point (see phase change), boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons are so energized that they leave their parent atoms from within the gas. A pure gas may be made up of individual atoms (e.g. a noble gas or atomic gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or compound molecules made from a variety of atoms (e.g. carbon dioxide). A gas mixture would contain a variety of pure gases much like the air. What distinguishes a gas from liquids and solids is the vast separation of the individual gas particles. This separation usually makes a colorless gas invisible to the human observer. The interaction of gas particles in the presence of electric and gravitational fields are considered negligible as indicated by the constant velocity vectors in the image.

A van is a kind of vehicle used for transporting goods or people.

In British English usage, it can be either specially designed or based on a saloon or sedan car, the latter type often including derivatives with open backs (such as pick-up trucks). There are vans in all shapes and sizes, ranging from the classic van version of the tiny Mini to the five metre long (LWB) variants of the Mercedes Sprinter van. Vehicles larger than this are classified as lorries (trucks).

The word van is a shortened version of the word caravan, which originally meant a covered vehicle.

The word van has slightly different, but overlapping, meanings in different forms of English. While the word always applies to boxy cargo vans, the most major differences in usage are found between the different English-speaking countries.

British English speakers will generally refer to a passenger minivan as a people-carrier or MPV, or multi-purpose vehicle, and a larger passenger van as a minibus. Ford makes a distinct line of vans with short bonnets (hoods) and varying body sizes. Minivans are the same vans but smaller. The driver's mate of a delivery van was sometimes referred to as a "vanguard." The Sun newspaper introduced the idea of "White Van Man", a typical working class man or small business owner who would have a white Ford Transit, Mercedes Sprinter or similar panel van. The Top Gear TV programme did a piece where the presenters had to buy a cheap panel van and then perform a series of tests. In reference to the reputation of van drivers' style of driving on British roads, one of the tests was to tailgate a car travelling at 60 mph as closely as possible.