Explain the meaning of change in quantity demanded

Explain the meaning of change in quantity demanded. How does it affect demand curve?

Change in quantity demanded means change in demand due to change in own price of the commodity, keeping other factors constant. This results at more being demanded at reduced price (extension in demand) and less being demanded at demand). Change in quantity demanded causes a movement along the same demand curve. Extension in demand causes rightward movement (point A to C), whereas, contraction in demand causes leftward movement (point A to B).