Average utility is obtained by dividing the total utility by number of units consumed.

Cardinal utility says that utility can be measured numerically.. it means it 's possible to know exactly the number of units of utility that a commodity or service has for a consumer. The unit measurements of utility is called 'util '.

The concept of marginal utility grew out of attempts by economists to explain the determination of price. The term “marginal utility ”, credited to the Austrian economist Friedrich von Wieser by Alfred Marshall, was a translation of Wieser 's term “Grenznutzen ”(border-use).

An indifference curve is a graph showing combination of two goods that give the consumer equal satisfaction and utility. Each point on an indifference curve indicates that a consumer is indifferent between the two and all points give him the same utility.

Consumer surplus is defined as the difference between the total amount that consumers are willing and able to pay for a good or service (indicated by the demand curve) and the total amount that they actually do pay (i.e. the market price) it is also known as buyer 's surplus.

An indifference curve shows a combination of two goods that give a consumer equal satisfaction and utility thereby making the consumer indifferent. Each indifference curve is convex to the origin, and no two indifference curves ever intersect. Along the curve, the consumer has no preference for either combination of goods because both goods provide the same level of utility.

The law of diminishing marginal utility states that with the consumption of every successive unit of commodity yields marginal utility with a diminishing rate. However, there are certain things on which the law of diminishing marginal utility does not apply. 

Consumer's equilibrium means:
Consumer's equilibrium refers to the position of rest or maximum satisfaction that a consumer achieves when consuming a combination of goods and services. It is the point at which the consumer allocates their income in a way that maximizes their utility or satisfaction.
Explanation:
Consumer's equilibrium is determined by the following factors:
1. Income: The consumer's income determines the amount of goods and services they can afford to consume. It is important to note that consumer's equilibrium is not dependent on the absolute level of income, but rather on the allocation of income among different goods and services.
2. Prices: The prices of goods and services also play a crucial role in determining consumer's equilibrium. The consumer will allocate their income in such a way that the marginal utility per unit of money spent on each good or service is equal. This is known as the principle of equimarginal utility.
3. Tastes and preferences: The consumer's tastes and preferences influence their choices and determine the utility they derive from consuming different goods and services. Consumer's equilibrium is achieved when the consumer allocates their income in a way that maximizes their overall satisfaction, based on their individual preferences.
4. Diminishing marginal utility: The concept of diminishing marginal utility states that as a consumer consumes more of a particular good or service, the marginal utility derived from each additional unit decreases. Therefore, the consumer will allocate their income in such a way that the marginal utility per unit of money spent is equal across different goods and services.
In conclusion, consumer's equilibrium is the position of maximum satisfaction that a consumer achieves when allocating their income among different goods and services. It is determined by the consumer's income, prices of goods and services, tastes and preferences, and the principle of equimarginal utility.

Utility, in ordinary sense, means usefulness. But, in economics, it means want-satisfying power of a commodity or service —the power to satisfy a human want. Utility is addable. One can add utility obtained from each unit of a commodity to get total utility obtained from the entire stock. In other words, by adding marginal utility from successive units, we obtain total utility of the stock.

A budget constraint represents all the combinations of goods and services that a consumer may purchase given current prices within his or her given income. Consumer theory uses the concepts of a budget constraint and a preference map to analyze consumer choices.