Supply, demand and prices — Economics, 14–17 years
Prices often change when buyers want more or sellers offer less. Supply and demand give us a way to reason about those changes without pretending that one cause explains every market.
Two sides of a market
Demand describes how much buyers are willing and able to buy at different prices. Supply describes how much sellers are willing and able to offer at different prices. Where the two plans meet, a market may settle on a price and quantity, although real markets can be messier.
Why prices move
Markets need some way to coordinate people who do not know one another. A price can signal that a product is scarce, popular, costly to make or easy to find. Supply-and-demand reasoning grew from the problem of explaining changing prices and shortages, rather than treating price as a fixed fact.
A strawberry shortage
A market normally sells 100 boxes at €3 each. A frost destroys part of the crop, so sellers can offer only 60 boxes at that price. Buyers still want 100, so boxes are scarce; sellers may raise the price, and some buyers leave, until the quantity wanted matches the smaller supply.
The trap: one curve does everything
People often say “demand went up” when they mean buyers purchased more because the price fell. That is a reasonable mix-up: both events appear together on a graph. A change in price usually means movement along a curve; a change in income, tastes, weather or costs can shift the whole curve.
Where it helps
This model helps explain why hotel rooms cost more during a festival, why umbrellas may become scarce during heavy rain, or why a new harvest can lower food prices. It is a starting model, not a promise: rules, market power, contracts and fairness can all affect the final result.
Keep exploring
Other languages
Loading MyLeoNes™…