This book is based on part of a course on Non-Destructive Testing (NDT) presented to fourth year Mechanical and Aerospace undergraduate students in Nanyang Technological University, Singapore. This book will cover the principles and applications of the widely used Non-Destructive Testing techniques. The basic techniques will be covered i.e. Liquid Penetrant, Magnetic Particle Inspection, Eddy Current, Radiography and Ultrasonics. In addition the newer advanced techniques such as Acoustic Emission, Real Time Radiography, Time of Flight Ultrasonics, Thermography and Laser Shearography will be presented. Also some software applications and automated systems developed in Singapore will be described. The techniques will be described in terms of their abilities to test welds, castings, fibre reinforced composites and electronic components. The advantages and disadvantages of each technique will be described and comparisons made between the techniques. This book would be suitable for industrialists who are involved with NDT in any way. It should be of particular interest to personnel from the metal and non-metal fabrication industries.