What are the importance of Utility Functions in the fields of Microeconomics?

Question

also, kindly give me some websites that can prove its importance... thank you very much! :)

Answer 1

utility function is very important in defining indifference curve and hence the demand curve.  . . .

secondly it also describes the consumer behaviour in different situations relating their income and prices.

thirdly it also helps in finding allocative efficiency and pareto optimality.