Supply
The quantity of a good producers are willing and able to sell at each price, holding other factors constant.
Exam items almost always force the “movement along vs. shift” decision: a change in the good’s own price moves you along a fixed supply curve (a change in quantity supplied), whereas a change in input prices, technology, the number of sellers, producer expectations, or prices of related goods in production shifts the whole curve. The classic tell is a vignette naming a non-price cause — read for it, then pick “shift,” not “movement.” Watch the direction trap: a fall in input cost or a productivity gain shifts supply right (more at every price), which by itself pushes equilibrium price down.
Don’t confuse supply with demand: their determinants are different lists, and supply slopes upward while demand slopes downward, so they answer opposite shift questions. Also separate a single-curve shift from equilibrium analysis — the exam may shift supply only and ask for the new price/quantity, where supply rises but demand stays put. Memory hook: supply Sells, demand Demands — sellers want high prices, so supply rises with price.
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