Determine the concepts of demand

• Demand always mentions to demand at price. The term 'demand' has no meaning unless it is related to price. For example, the statement, 'the weekly demand for potatoes in city X is 10,000 kilograms' has no meaning unless we specify the price at which this quantity is demanded.
• Demand always suggests demand per unit of time. So it is vital to specify the period for which the commodity is demanded. For example, the statement that demand for potatoes in city X at 8$ per kilogram is 10,000 kilograms again has no meaning unless we state the period for which this quantity is being demanded. A complete statement would thus be as follows: 'the weekly demand for potatoes in city X at 8$ per kilogram is 10,000 kilograms'. It is essential to specify the price and the period since demand for a commodity would be different at different prices of that commodity and for different periods of time. So we can define demand as follows: "The demand for a commodity at a given price is the amount of it which would be bought per unit of time at that price".