The transformation of conception into write-up brings forth a book. Writing a book is an art which manifests your wisdom, perception, knowledge, intellect and maturity judged by reader in colleges / universities and in the community. It promots writer’s proficiency to pose worth while questions and fosters ability to explain complex notions to readers. It refines ideas looks forward to readers needs and permits evaluation of the adequacy of arguments put forth. Writing equips the writer with communication skills. A book is thus a mode of Communication between the author and readers. Contents - Part - I 1. Introduction 2. Cardinal Utility Analysis 3. Ordinal Utility Analysis 4. Consumer’s Optimum Part - II 1. The Income Effect 2. The Substitution Effect 3. The Price Effect 4. Duality In Consumer Demand Theory 5. Derivation of Demand Curve Part - III 1. The Cobb-Douglas Utility Functions 2. The Constant Elasticity of Substitution Utility Function 3. Theory of Demand 4. Elasticity of Demand 5. Contemporary Theory of Demand About the Author: Prof. Anubhuti Ranjan Prasad Former Head ,in the Department of Economics, Faculty of Social Sciences, , Banaras Hindu University is a B.A. (Honour) in 1973 from Ranchi University and obtained his Master’s degree from the same University in 1975 . He has taught Microeconomics and Quantitative Economics to undergraduate and postgraduate students of Economics over past four decades . Recipient of Banaras Hindu University Fellowship in 1977 and thereafter Junior Research Fellowship (JRF) of the University Grants Commission (UGC) in 1978 , Dr Prasad has a brilliant academic career and obtained his Ph.D degree in Economics in 1982 from Banaras Hindu University and was conferred the BEST THESIS AWARD .He has several publications to his credit in leading international and national journals , and published six books related to Microeconomics and Quantitative Economics. Dr.Ishi Mohan is an Assistant Professor at Faculty of Commerce (FOC), Banaras Hindu University,Varanasi.She has done her M.Com. From faculty of Commerce,BHU with THREE GOLD MEDALS of the university. After qualifying the UGC-NET examination in Commerce stream , she has completed her Doctoral research from Faculty of Commerce, BHU. She has designed and taught courses of business Economics , Finance , Organizational Behaviour, etc Her current research interest related with Stock Market Behaviour, Business Finance and Economics. She has nearly dozen publication to her credit.Dr. Mohan has over a decade experience of teaching and research.