Why do supply and demand curves slope in opposite directions?

Supply and demand curves slope in opposite directions due to the fundamental behaviors of consumers and producers. The demand curve slopes downward because, as prices decrease, consumers are willing to purchase more of a good, reflecting the law of demand. In contrast, the supply curve slopes upward because higher prices incentivize producers to supply more of a good, reflecting the law of supply. This interplay illustrates how market equilibrium is reached where supply meets demand.