A fundamental economic theory proposed by Adam Smith. The supply curve slopes upward, while the demand curve slopes downward. The intersection of these two curves determines the market equilibrium price and quantity.
📖 Standard Introduction
Supply and Demand theory is the core theory of microeconomics that describes the mechanism determining market prices and transaction quantities. The supply curve represents the quantity of goods producers are willing to supply at different price levels, typically sloping upward (higher price leads to more supply). The demand curve represents the quantity of goods consumers are willing to purchase at different price levels, typically sloping downward (higher price leads to less demand). The intersection point of these two curves is called the market equilibrium point, which determines the equilibrium price and quantity. Supply and Demand theory also includes important concepts such as elasticity (price elasticity of demand, price elasticity of supply), consumer surplus, and producer surplus, serving as fundamental tools for analyzing market mechanisms, government intervention effects, tax incidence, and other issues.
💬 Simplified Explanation
Supply and Demand theory explains "how prices are determined". Imagine a vegetable market: If tomatoes are very expensive, farmers are willing to grow more (supply increases); but consumers buy less because they find it expensive (demand decreases). If tomatoes are very cheap, farmers are unwilling to grow them (supply decreases), but consumers buy more (demand increases). Eventually, there will be a "just right" price where the quantity sellers are willing to sell equals the quantity buyers are willing to buy - this is the "equilibrium price". If suddenly everyone wants to eat tomatoes (demand increases), prices will rise; if there's a bumper tomato harvest this year (supply increases), prices will fall. This simple principle explains price changes for nearly all goods in a market economy.
Adjust Parameters
Current Market Status
📈 Demand Curve
Represents the quantity of goods consumers are willing to purchase at different prices. Higher price leads to lower demand.
- Slopes downward
- Affected by income, preferences, substitutes
- Elasticity indicates sensitivity to price changes
📊 Supply Curve
Represents the quantity of goods producers are willing to supply at different prices. Higher price leads to more supply.
- Slopes upward
- Affected by costs, technology, expectations
- Elasticity indicates flexibility of production adjustment
⚖️ Market Equilibrium
The intersection of supply and demand curves, where the market clears with no surplus or shortage.
- Equilibrium Price: Price when supply equals demand
- Equilibrium Quantity: Quantity of goods traded
- Market automatically adjusts to reach equilibrium