When there is a change in demand for a normal good, it means that the entire demand curve for the good shifts either to the left or to the right. This shift can be caused by a variety of factors, such as changes in consumer preferences, income levels, or market conditions. The shift in the demand curve means that at each price level, the quantity demanded has changed. This is different from a movement along a given demand curve, which occurs when there is a change in the price of the good and results in a change in the quantity demanded, but not a shift in the entire demand curve.