Purpose - To illustrate the importance of nanometrology, the discipline of metrology at the nanoscale, and to describe the techniques involved. Design/methodology/approach - This firstly highlights the importance of nanometrology and considers some future applications with particularly demanding metrological requirements. The main techniques used to characterise nanoscale devices are described. Research and the activities of certain national metrology institutes are discussed. Findings - This illustrates that nanometrology is a critical discipline that will underpin the nanotechnology revolution. It shows that a range of techniques exist for characterising nanomaterials and devices, although most are costly and complex. It further shows that nanometrology developments are underway on a global scale. Originality/value - This paper demonstrates the importance of nanometrology and describes in detail the techniques used.