Key terms & glossary

A quick reference for the vocabulary that shows up again and again. Come back here whenever a term stops making sense.

• Opportunity cost — the value of the best alternative you gave up.
• Marginal — the effect of one more unit (one more hour, one more slice).
• Equilibrium — a state with no pressure to change; supply meets demand.
• Ceteris paribus — “all else equal”, the assumption that lets us isolate one cause.