Supply is the producer's side of the market equation. It represents how much of a good or service businesses are willing to produce and sell at different prices. Higher prices generally motivate producers to supply more — that is the law of supply.
The law of supply states: when prices rise, supply increases (and vice versa), all else being equal. If wheat sells for $5/bushel, a farmer might plant 100 acres. At $10/bushel, they plant 200 acres. Higher prices mean higher profits, incentivizing more production.
Factors that shift supply: input costs, technology, number of suppliers, government regulations, and natural events. A drought destroys crops — supply shifts left (decreases), prices spike. A new manufacturing technology makes production cheaper — supply shifts right (increases), prices fall. The COVID-19 pandemic caused massive supply chain disruptions, demonstrating how supply shocks ripple through the global economy.