Rationing is the controlled distribution of scarce resources, goods, services, or an artificial restriction of demand. Rationing controls the size of the ration, which is one's allowed portion of the resources being distributed on a particular day or at a particular time. There are many forms of rationing, although rationing by price is most prevalent.
Romanian ration card, 1989
A 1918 advertisement urges civilians to preserve their food during World War I.
First World War German government propaganda poster describing rationing with personifications of meat, bread, sugar, butter, milk, and flour, 1916
Child's ration book, used in Britain during the Second World War
In microeconomics, supply and demand is an economic model of price determination in a market. It postulates that, holding all else equal, in a competitive market, the unit price for a particular good or other traded item such as labor or liquid financial assets, will vary until it settles at a point where the quantity demanded will equal the quantity supplied, resulting in an economic equilibrium for price and quantity transacted. The concept of supply and demand forms the theoretical basis of modern economics.
Adam Smith