We are happy that the 4th edition of the book "Electronic Devices and Circuits" is brought out, to meet recent revised syllabus. The contents and topics are revised so that there is almost one to one match between the syllabus and topics will match. This textbook will also be very useful for preparing competitive examinations like GATE, Engineering services exams and such other examinations. This book is also useful for AMIETE, AMIE (Electronics), M.Sc (Electronics), Polytechnic and Diploma programs in Electronics and B.Sc (Electronics) Courses. Salient Features: Objective Type Questions, Essay Type Questions and Conceptual questions and answers for such questions are given at the end of each chapter. · Questions from GATE examinations pertaining to the topics covered in the text book are worked out and solutions are given. · Appendices containing practical aspects of Electronic Components are given, which will make the students "Industry Worthy".