The mathematical equations which define the relationship of a function with its derivatives are known as differential equations. The varied types of differential equations include ordinary, partial, non-linear and linear differential equations. They have applications in diverse fields such as quantum mechanics, electrodynamics, economics, chemistry, etc. The book studies, analyses and upholds the pillars of differential equations and their utmost significance in modern times. Different approaches, evaluations and methodologies have also been included. In this textbook, constant effort has been made to make the understanding of the difficult concepts of this field as easy and informative as possible, for the readers.