This book has been written keeping in mind all points at which Student feel difficulty, efforts have been made to explain such points in depth so that the students can follow the subject easily we do not claim to express anything in Original but after going through many standard works on subject. We have satisfaction of making the book at around complete. It is sincerely hoped that this book will satisfy the need of the students and if it gives them even part of pleasure that The Author had in its preparations, we will consider his Labour rewarded.