"This book provides a systematic and clear presentation of Linear Differential Equations. It covers the fundamental concepts and standard methods for solving differential equations with constant coefficients. The subject has been developed in a simple and logical manner, making it suitable for undergraduate students. Each method is explained step by step to ensure better understanding and clarity. The book includes important techniques such as the operator method, method of undetermined coefficients, method of variation of parameters, and equations reducible to linear differential equations with constant coefficients. It also covers simultaneous linear differential equations with constant coefficients. A large number of illustrative examples and exercises have been included to help students practice and strengthen their problem-solving skills. The solutions are presented in a structured and easy-to-follow format. This book is primarily intended to help students build a strong conceptual foundation and perform well in university examinations."