In general, there is an opinion that Calculus is a tremendously difficult subject, probably because the required number of good teachers and good books are not available. We know that books cannot replace teachers, but we are of the belief that good books can definitely reduce dependence on teachers, and students can gain more confidence by learning most of the concepts on their own. Calculus is the higher branch of mathematics, which enters into the process of calculating changing quantities (and certain properties), in the field of mathematics and various branches of science, including social science. In the market hundreds of books are available on Differential Calculus. All these books contain a large number of important solved problems. Besides, the rules for solving the problems and the list of necessary formulae are given in the books, without discussing anything about the basic concepts involved. Of course, such books are useful for passing the examination(s), but Calculus is hardly learnt from these books. The books aim to show them the enjoyment in the beauty and power of Calculus and develop the ability to select proper material needed for their studies in any technical and scientific field, involving Calculus and avoid the difficulties that will hook a student’s interest. The author’s aim throughout has been to provide a tour of Differential Calculus for beginner. This book appreciates to the fundamental concepts and applications of Differential Calculus in a comprehensive and easiest way to understand.