Differential Equation is a mathematical equation which denotes the relationship between a function and its derivatives. The functions usually represent physical quantities in the applications and the derivatives are used to show the rate of change. The study of differential equations involves pure and applied mathematics, physics and engineering. There are various types of differential equations such as ordinary differential equations, partial differential equations, linear differential equations and non - linear differential equations. Ordinary differential equation is an equation that contains unknown function of one real or complex variable. Partial differential equations are the differential equations that involve unknown multivariable functions and their partial derivatives. Linear differential equations are linear in the unknown function and its derivatives, whereas non - linear differential equations are formed by the products of the unknown function. This book unravels the recent studies in the field of differential equations. It elucidates new concepts and their applications in a multidisciplinary manner. It will serve as a valuable source of reference for graduate and post graduate students.