Demand is the total amount of goods or services which people want to buy, for a set price. The demand for an item indicates how much it is needed or wanted. This is important in economics, because the law of supply and demand will decide the price at which something will be bought and sold.
Demand is the amount of goods that people want to buy at a given price. Prices go up when supply is less, and demand is more. It follows the law of demand where as price increases, demand decreases and vice versa showing an inverse relationship between quantity demanded and price. This is known as the law of demand which assumes that the consumer will want more. Demand forecasting tries to predict how demand will change in the future.
Sometimes the demand does not change much no matter what the price is. One example is when people are addicted to illegal drugs. These people need to get their drugs, they will pay any price they can afford. This effect is known as elasticity.