Utility of a commodity

UTILITY :

What is  utility ?

It is the ability or property of a commodity or service to satisfy a want.
# It is the satisfaction that a person derives from the consumption of a good or service.
# It varies from person to person , place to place and time to time.

▪Difference Between Cardinal Utility & Ordinal Utility :

When the utility can be measured in quantitative terms it is called cardinal utility whereas when the utility cannot be measured in quantitative terms it is called ordinal utility.

▪ Relationship Between Demand & Utility     
     Of A Commodity :

The quantity of a commodity demanded depends upon its utility.
There is a direct relationship between utility and quantity demanded of a commodity i.e., higher the utility , higher will be the demand for a commodity and lower the utility ,lower will be the demand for a commodity.

▪ Law Of Diminishing Marginal Utility :
First let us understand what is marginal utility
  Marginal utility - utility derived from the consumption of an additional unit is called marginal utility.
Now let us move to The law of diminishing marginal utility.

- The law states that "the additional utility which a person derives from a given increase of his stock of anything diminishes with every increase in the stock that he  already has".
In simple words, when a consumer goes on consuming a particular commodity without any time gap , the additional unit of the same commodity gives him less and less satisfaction.
# the shorter the time period , the more quickly marginal utility diminishes.