Supply & Demand
The core mechanism behind every price you've ever paid.
2 min read
Core question: why does a price settle where it does, instead of anywhere else?
The metaphor: two crowds pushing on a door
Picture a door with people pushing from both sides. On one side, buyers push harder the cheaper the price gets — more people want in at a bargain. On the other side, sellers push harder the more expensive it gets — more people are willing to sell if the reward is bigger. The door settles wherever the two pushes exactly cancel out. That resting point is the price.
Push either crowd harder — more buyers show up, or sellers become scarcer — and the door slides to a new resting point. Nobody decided the new price. It's just where the pushing balances again.
No single person sets the market price of wheat, oil, or a stock. It emerges from thousands of independent pushes finding their balance point — which is why prices can shift overnight without anyone "deciding" to change them.
Why shortages and gluts are the same phenomenon
A shortage is just the door stuck too far toward the buyers' side — the price is artificially low, so more people want in than the sellers' side can supply. A glut is the mirror image: price stuck too high, sellers piling up with no buyers pushing back. Both are the same mechanism, just displaced from the balance point — usually by something external holding the price fixed (a price cap, a subsidy, a shock to supply).
Next time you see a shortage in the news, ask: is demand suddenly rising, or is something stopping the price from finding its natural balance point?
Why this is worth understanding
Once you see price as a balance point rather than a fixed fact, a lot of economic behavior stops being mysterious: why gas prices spike during shortages, why concert tickets get scalped, why a heatwave moves the price of ice cream. It's always the same two crowds, pushing.