It gives me immense pleasure to bring out the nineteenth edition of the book with significant changes in some parts. My efforts have been to incorporate fully the latest changes in the syllabi of B.A.(Hons.) Economics and B.Com. (Hons.) of the universities. Besides, revising the book for nineteenth edition has given me an opportunity to incorporate the various topics of UGC new syllabi of B.A. (Hons.) Economics, B.Com. (Hons.) and B.A. (Hons.) Business Economics under the 'Choice Based Credit System' (CBCS) which is to be adopted by all India Universities with making up to 30 per cent changes in them, if they so desire.

On the important suggestion of the fellow colleagues from Delhi and other Indian universities, I incorporated in a previous edition a new comprehensive chapter (given as Appendix to Chapter 3) on "The Use of Mathematical Concepts, Graphs and Other Techniques in Economics." In it, I have explained the use of graphs in economics, various types of curves and measurement of their slopes, the concept of function, both linear and power functions, the concept of derivatives and the use of differential calculus as optimising technique for solving the problems of maximisation and minimisation in economics. I hope the study of this appendix will enable the students to understand various economic theories better as economics in recent years has become increasingly mathematical.