Final answer:
The demand curve on a supply and demand graph shifts due to changes in demand determinants like income or consumer preferences. An increase in demand shifts the curve right, while a decrease shifts it left. Movements along the demand curve indicate changes in the quantity demanded due to price changes of the good itself, with other factors constant.
Step-by-step explanation:
The movement of the demand curve on a supply and demand graph is influenced by various factors known as demand determinants. These include changes in income, consumer preferences, prices of related goods, and expectations, among others.
When any of these factors change, assuming all other factors remain the same (ceteris paribus), the entire demand curve can shift. For instance, if there's economic growth and people's incomes rise making them able to afford more luxury items like cars, the demand for these goods would increase. Graphically, this is represented by a shift of the demand curve to the right, from D0 to D1, indicating at each price, more of the goods are being demanded than before. Conversely, a decrease in demand would shift the curve to the left.
Movements along the demand curve, on the other hand, represent changes in the quantity demanded due to price fluctuations of the good itself, while other economic factors stay constant. If the price of the good decreases, there will be a movement down along the demand curve indicating a higher quantity demanded. Conversely, a price increase will cause a movement up along the curve indicating a lower quantity demanded.