vitÂ·riÂ·fy (vÄ­tâ²rÉ-fÄ«â²) v. vitÂ·riÂ·fied, vitÂ·riÂ·fyÂ·ing, vitÂ·riÂ·fies v.tr. To change or make into glass or a glassy substance, especially through heat fusion. v.intr. To become vitreous.
We draw a demand curve to show the relationship between the price of the good and the quantity that consumers are willing to buy. For example, suppose people are willing to buy 20 pounds of strawberries at a price of $2, but are willing to buy 30 pounds if the price falls to $1.
Shift in the Demand Curve. A shift in the demand curve occurs when the whole demand curve moves to the right or left. For example, an increase in income would mean people can afford to buy more widgets even at the same price.