Explain about the increases or decreases or shifts in demand terminology.

Market into equilibrium P₁Q₁, here demand D₁ equals supply S₁

• When price reduce fromP₁ to P₃ there would be an extension of the demand curve like the quantity demanded would increase by Q₁to Q₃ due to the fall within price

• When there was a price increase by P₃ to P₁ there would be a contraction of the demand curve, in that case the quantity demanded would fall by Q₃ to Q₁ due to the rise in price

• An increase or shift to the right of the demand curve by D₁ to D₂ as a rise into demand at similar market price P₁ would finally create a higher price and quantity now demanded, settling at last P₂Q₂ once new equilibriums determined, because of a shortage.

• A reduce or shift to the left of the demand curve by D₁ to D₃ (a reduce in demand at similar market price P₁) would at last create a lower price and quantity currently demanded, settling at last P₄Q₄ when a new equilibriums  found, because of a surplus.