The principles of signal digitization as they relate to digital television are presented in such a way as to lay groundwork for future digital television papers. To clarify the steps that are involved, a hypothetical “manual” conversion of an analog signal to its digital equivalent is examined. For sampling color television signals, the best sampling rate is considered to be exactly three times the color subcarrier frequency. Various methods of digitization are mentioned, and those suitable for wideband signals are defined. Quantization error and the problems of noise and noise measurement are discussed. The great advantage of handling television signals digitally is that digital quantities are capable of being sent, received, switched, stored, recorded and delayed virtually without distortion. Whatever bad effects accrue from conversion to and from the digital mode need accrue only once. Whatever ills can befall a digital signal, short of total loss, they can be made invisible and they do not accumulate.