перевести на русский Consumer demand is the quantities of a particular good that an individual consumer wants and is able to buy as the price varies, if all other factors influencing demand are constant.

That is, consumer demand is the relationship between the quantity demanded for the good and its price. The factors assumed constant are prices of other goods, income, and a number of noneconomic factors, such as social, physiological, demographic characteristics of the consumer in question (о котором идет речь).

The theory of demand is based on the assumption that the consumer having budget constraint seeks to reach the maximum possible level of utility, that is, to maximize utility, but he usually prefers to obtain more rather than less. The consumer has to solve the problem of choice. Provided he is to maintain a given level of utility, increases in the quantity of one good must be followed by reductions in the quantity of the other good. The consumer has to choose the specific goods within the limits imposed by his budget.

The concept of marginal utility is of great importance for solving the utility maximization problem. The marginal utility of a good is the additional utility obtained from consuming an additional unit of the good in question. The marginal utility from consuming a good decreases as more of that good is consumed. The income should be allocated among all possible choices so that the marginal utility per dollar of expenditure on each good is equal to the marginal utility per dollar of expenditure on every other good.

A price increase will result in a reduction in the quantity demanded. This relationship between the quantity demanded of a good and its price is called the law of demand. As the marginal utility from each additional unit of the good consumed decreases, the consumer will want to buy more of this good only if its price is reduced.

Market demand is the quantities of a good that all consumers in a particular market want and are able to buy as price varies and as all other factors are assumed constant. Market demand depends not only on the factors affecting individual demands, but also on the number of consumers in the market. The law of demand also works with market demand.