This paper will describe the various active techniques and procedures used to stimulate materials in order to receive a thermal response. Some of the recent developments in IR/T technology and detectors will be described, such as high resolution focal plane detector arrays and the much anticipated uncooled detectors. An overview of many practical IRNDT quality assurance applications for various industries will be discussed, such as voids and delaminations in composites, weld inspections, coating thickness and bond integrity, plastics, turbine blades, cooling tube blockages and material flaw detection.