Waveform metrology is the traceable characterization of dynamic electrical signals. The waveforms are measured either as voltage vs. time or as a complex (magnitude and phase) frequency spectrum, and the instrumentation calibration is traceable to SI primary standards. Waveform metrology evolved from parametric measurements of transition-duration for specification purposes. This chapter describes the development of waveform metrology and previous work on impairments and correction algorithms for digital instrumentation, such as real-time digital oscilloscopes, used in THz communication metrology. Traceability has driven the need for point-by-point uncertainties, building on the Guide to Uncertainty in Measurements (GUM) and its annexes, to link uncertainty contributions from both the time and frequency domain measurements.