Abstract In the past 30 years, ultrasound has become a very powerful imaging modality, due mainly to its unique temporal resolution, low cost, non-ionising characteristics and portability. Understanding the physical details of the acoustic wave–tissue interaction is necessary to realise the full potential of ultrasound techniques, which have steadily improved in terms of quality and range of applications in recent years. In this paper, we give an overview of the fundamentals of diagnostic ultrasound and a brief summary of its applications and methods aimed at tissue characterisation. Besides more conventional techniques such as A-mode, B-mode and M-mode, recent successful advances such as harmonic imaging, three-dimensional visualisation, elasticity imaging and the use of contrast agents are discussed. With these technological improvements, ultrasound techniques will be able to provide high-quality diagnostic tools in everyday clinical practice.