Infrared thermography is an imaging technique that utilizes the distribution of infrared radiation emitted by an object. Any body with a temperature higher than 0 K emits electromagnetic radiation, the spectrum of which depends on its temperature and emissivity. A thermal imaging device (thermal imaging camera/infrared radiation detector) detects infrared radiation emitted by the examined body, based on thermal or quantum effects. The result of infrared thermography measurement is referred to as a thermogram, or thermal image, where different temperatures are represented in different colours or shades of grey. Infrared thermography can detect changes in the temperatures of different parts of the body. Increased warmth is usually associated with enhanced vascular perfusion and inflammation (autoimmune diseases, endocrine disorders, orthopedic injuries). At the same time, infrared thermography can also locate areas characterized by reduced blood flow. The first part of the article presents the basics of infrared thermography and describes the possibilities of its use in angiology, internal diseases, aesthetic and reconstructive surgery, dermatology, as well as physiotherapy and rehabilitation.