What supply and demand actually mean
Demand: how many people want to buy, and how badly. If lots of people want a particular figurine, demand is high.
Supply: how much there is to sell. If the factory only made 1,000 units, that's all the market can buy—supply is limited.
How supply and demand push prices around
More buyers, but no more goods → prices rise. A hot concert has only a few thousand seats and hundreds of thousands fighting for them, so scalped tickets get bid sky-high—that's demand far outstripping supply.
More goods, but no more buyers → prices fall. During end-of-season clearance the clothes pile up, and stores have to cut prices just to move them.
Scarcity: only what's both rare and wanted is truly expensive
Being "rare" alone doesn't make something expensive. Lots of people don't have a particular pebble from the roadside, but no one's fighting over it, so it's worthless. The condition for expensive is: rare and wanted at the same time.
Scarcity describes exactly that state of "not enough relative to the people who want it." A limited sneaker drops only a few hundred pairs while tens of thousands want them, so they get flipped at a markup.
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"This shoe is sold out everywhere—you just can't get it." Which side is this mainly about?
答案：Supply (very few goods to sell)
"Sold out, can't get it" refers to too few goods available to sell, which is the supply side.
"How many people want to buy, and how badly"—what is this called in this lesson? Fill in the blank.
答案：demand
Demand = how many people want it and how strong their willingness is; supply = how much there is to sell.
On a rainy evening rush hour, far more people want a ride while available cars barely increase. Fares tend to:
答案：Rise
Demand surges while supply is basically flat, so the seesaw tilts toward demand and prices go up.
True or false: When a product suddenly arrives in large quantities while the number of buyers barely increases, the price usually faces downward pressure.
答案：True
Supply rises while demand doesn't keep up, so the seesaw tilts toward supply and prices tend to fall.
By this lesson's reasoning, what does something usually need in order to be "truly expensive"?
答案：Both rare and wanted by many people
Scarcity stresses "not enough relative to those who want it." Only what's both rare and sought-after is truly expensive; rare with no buyers is worthless.
True or false: A bottle of water in the desert costs far more than the same one in a store mainly because, in the desert, water is so scarce relative to "the people who want to drink it."
答案：True
The same bottle of water is extremely scarce relative to demand in the desert, so it costs more. Scarcity is set by "people who want it vs. goods available."