The hidden cost of every choice
Every choice you make has a hidden cost: the best thing you gave up to make it. Economists call this opportunity cost, and it's the single most useful idea in this course.
Take a free concert ticket. It costs you nothing, or so it seems. But the evening you spend at the concert is an evening you can't spend working a paid shift, seeing a friend or sleeping before an important day. If any of those was worth more to you, the free ticket was expensive.
Once you start noticing opportunity costs, you make better decisions almost automatically. The question changes from "Is this worth it?" to "Is this worth more than the next best thing I could do?"
Incentives are everywhere
People respond to incentives. Change the reward or the penalty for doing something, and you change how many people do it.
That sounds obvious, but incentives often work in ways nobody intended. When a city pays a bounty for catching rats, some people start breeding rats. The lesson: always ask what behavior a rule actually rewards.
Why prices are what they are
A price is a signal. It tells buyers how scarce something is and tells sellers how much people want it.
When prices rise, buyers look for alternatives and sellers look for ways to supply more. That constant adjustment is what keeps shelves stocked without anyone planning it.