The demand curve is a graphical representation that shows the relationship between the total quantity of a particular product which consumers are able to buy and the price of such a product. The two major ways by which demand curve behaves is either there is a shift in the demand curve, or there is a movement along the demand curve.
The truth is both are not the same in terms of meaning. A movement along the demand curve is observed when there is a change in the price of a particular commodity without any change in the various factors that can affect the demand for such a commodity.
These factors include a taste of the consumers, income, change in the price of other related commodities. On the other hand, a shift in the demand curve is observed when there is a change in demand as a result of some factors that affect the demand for such commodities without any change in its price.