It is of great importance that both individual components and complete engineer­ ing assemblies and structures are free from damaging defects and other possible causes of premature failure. A whole series of inspection instruments and tech­ niques has been evolved over the years and new methods are still being developed to assist in the process of assessing the integrity and reliability of parts and assemblies. Non-destructive testing and evaluation methods are widely used in industry for checking the quality of production, and also as part of routine inspec­ tion and maintenance in service. Despite the obvious importance of the subject, and the fact that most of the inspection methods are based on well-established scientific principles, there is a dearth of publications suitable for use as texts in our universities and colleges. The whole area of non-destructive testing receives scant attention in many engineering degree and diploma courses in the UK and this may be a consequence of a shortage of student texts. The authors, in producing this basic text, hope that it will prove useful to students on engineering courses and, possibly, act as a stimulus for the more widespread introduction of the subject into curricula.