Shifts in demand curve
Shifts in the demand curve are brought about by the changes in factors like taste, prices of other related commodities, income etc other than the price of the commodity. The change in the demand for the commodity is indicated by a shift to the right or left of the original demand curve.
In the figure below, DD represents the initial demand before the changes. When the demand increases, the demand curve shifts to the right from position DD to positions D2D2. The quantity demanded at price P1 increases from q1 to q'1. Conversely, a fall in demand is indicated by a shift to the left of the demand curve from D2D2 to DD. The quantity demanded at price P1 decreases from q1 to q1