This chapter presents the fundamental concepts, devices and techniques underlying the measurement of temperature fields through infrared radiation detection. It introduces the primary physical principles governing infrared emission, including Planck’s and Stefan–Boltzmann’s laws, and discusses the role of emissivity and infrared optics, along with the key components of a thermal camera. The performance characteristics of thermographic systems are described, with guidance on selecting and using them appropriately for surface temperature distribution measurements. Dynamic thermography enables the detection not only of steady-state temperature fields but also of temporal fluctuations, capturing a “temperature video” that can reveal subsurface defects and surface stress fields. The chapter illustrates the main techniques for stress field measurement using dynamic and differential thermography and highlights a range of applications in experimental mechanics, structural component qualification, model validation, and beyond.