Consider the following: When "bell-bottom" pants went out of style in the 70s, the demand curve for bell-bottoms SHIFTED to the left, or more towards "zero", because people no longer wished to purchase these pants at any price. If, however, the price of bell-bottoms was increased, and all other factors remained unchanged, the quantity demanded of bell-bottoms at this price would decrease and be represented by MOVEMENT along the demand curve because there is an inverse relationship between price and quantity demanded.
On the other hand, if there was an increase in the price of labor, or wages, the supply curve for bell bottoms would SHIFT to the left, or more towards "zero" because the cost of inputs had increased. If the price of bell-bottoms, however, increased, producers would be willing to produce more bell bottoms because there is a positive relationship between price and quantity supplied. This would be represented by MOVEMENT along the supply curve.