1. UTILITY
   1. The satisfaction (benefit & satisfaction) obtained from the consumption of GoS
      1. More consumption -> More utility
   2. TOTAL
      1. Generally, total utility increases with more consumption of a GoS
      2. eventually
         1. DISLIKE, as utility decrease
2. MARGINAL UTILITY
   1. DEF
      1. The ADDITIONAL UTILITY an individual received from consuming 1 ADDITIONAL UNIT of GoS
   2. LAW of DIMINISHING MARGINAL UTILITY
      1. Consumers experience DIMINISING ADDITIONAL UTILITY
      2. as they consume more unit of a GoS, during a given time
   3. COMBINATION of GoS
      1. consumers choose to buy a combination of GoS
         1. -> maximise their utility
      2. factors
         1. PREFERENCE
         2. BUDGET CONSTRAINTS
            1. HH's consumption is limited by
            2. the budget available
            3. the price of the GoS
            4. HH can't afford anything beyond the BUDGET LINE
         3. determined
            1. the level of UTILITY
            2. obtained by a GoS
   4. MAXIMISE MARGINAL UTILITY
      1. MARGINAL UTILITY PER UNIT
         1. eg; marginal utility per $
      2. TWO conditions
         1. The marginal utility per $ spent on all Gs are goods are equalised => BALANCE !!!
         2. [Spending on X] + [Spending on Y] = Total amount of disposable budget
3. MRS
   1. consumer is ready to give up one good IN EXCHANGE for another while maintaining the same level of utility
   2. hypothesis
      1. MRS = 1
         1. indifferent between changing X or Y
      2. MRS > 1
         1. changing X requires more Y
      3. MRS < 1
         1. `changing X requires less Y
   3. MRS vs Price
      1. effect
         1. Utility is maximised when
            1. MRS = price ratio
4. UTILITY & DC
   1. total utility
   2. budget constraints
   3. GIFFEN G
   4. optimal consumption