[en] The International Atomic Energy Agency (IAEA) has been active in the promotion of non-destructive testing (NDT) technology for many decades. The prime reason for this interest has been the need for stringent quality control standards for safe operation of nuclear as well as other industrial installations. The IAEA has successfully executed a number of projects, including technical cooperation projects (national and regional) and coordinated research projects, in which NDT was an important part. Through these projects, a large number of persons have been trained in numerous Member States, leading to the establishment of national certifying bodies responsible for training and certification of NDT personnel. Consequently a state of self-sufficiency in this area of technology has been achieved in many of these States. All along there has been a realization of the need to have well established training guidelines and related books, in order, first, to guide IAEA experts involved in this training programme and, second, to achieve some level of international uniformity and harmonization of training materials and consequent competence of NDT personnel. The syllabuses for training courses have been published in the form of TECDOC publications. The first was IAEA-TECDOC-407 (1987), which contained syllabuses for the five basic NDT methods: liquid penetrant testing, magnetic particle testing, eddy current testing, radiographic testing and ultrasonic testing. To accommodate advancements in NDT technology, later versions of this publication were issued in 1991, 2002 and 2008, with the current version being IAEA-TECDOC- 628/Rev.2 (2008), which includes additional and more advanced NDT methods. The next logical step was to compile textbooks and training manuals in accordance with these syllabuses. Manuals on liquid penetrant, magnetic particle, radiographic, ultrasonic and eddy current testing have already been published in the Training Course Series. These play a vital role in training and certification of NDT personnel in Member States. The compilation of this book was a continuation of that effort. The first draft of the book was prepared by the National Centre for Non-Destructive Testing, Pakistan. This was reviewed and finalized at a consultants meeting held in Vienna on 23-27 August 2010. The section in the previous Training Course Series publications on general knowledge related to NDT, comprising an introduction to basic NDT methods, materials, manufacturing processes and quality assurance, has been revised with updated information