Primarily intended for the undergraduate students of mathe-matics and engineering, this textbook meets the needs of a one-term course in partial differential equation. No specific prerequisite except basic calculus is required to understand this textbook. In this book, author has tried his best to preset all related formula with few standard examples worked out according to the derived formula to make the book precise. The notations used in this textbook are commonly used by mathematicians. Considerable use has been made of illustrations to stimulate the students’ visual understanding of partial differential equation. The book includes numerous examples and problems. Some standard problems with sufficient hints have been included at the end of each section to gauge the students’ understanding and grasp of the theory. This book will truly fulfil the requirement for an accessible textbook suitable for courses all over the universities in India.