1. Demand is defined as the quantity of a good purchased at a given price at a given time. It has three components: quantity, price, and time.
2. Factors that affect individual demand include: price of the good, price of related goods, income of the buyer, and tastes/preferences. Demand increases when price decreases and decreases when price increases.
3. Market demand is the total quantity demanded by all buyers in the market. It is affected by the number of buyers, distribution of income/wealth, and climatic conditions.