The text covers the standard topics on ordinary differential equations with a wealth of applications drawn from engineering and sciences.PedagogicaI Approach This bookintended as a friendly introduction to dif-ferential equations within the context of science and engineering. It dwells more on intuition rather than rigor， The emphasis is kept on the conceptual ar-guments in order to develop an intuitive understanding of the subject matter.The text strives to be simple and understandable， and encourages creative thinking. The authors believe that legal documents such as a rental lease agreements intended for plain people should be written in plain English instead of being written in a precise legal language that is beyond most peo-ple's grasp and requires a lawyer to translate， Likewise， a differential equa-tions textbook should be written for the student to read and understand.Instructors do not need textbooks， students do. It is common experience that students flip through the pages of a mathematics textbook only when they are trying to find an example similar to the problem assigned. It is often stated that mathematical concepts must be explained in plain language to have a lasting impression.