ISO 7637-1 is the introductory part of the ISO 7637 series on electrical disturbances from conduction and coupling in road vehicles. It does not itself define a test; its function is to establish the vocabulary and the general framework that the subsequent parts rely upon, so that the test waveforms, the coupling mechanisms and the operating conditions are described consistently across the series. The document explains the distinction between disturbances that are conducted along the supply lines and those transmitted by capacitive or inductive coupling through other conductors, describes the practical origins of the transient activity in the vehicle, including the switching of inductive loads, the operation of relays and motors and the interruption of current in a circuit with significant inductance, and sets out the principles by which representative test conditions are defined. It also introduces the concepts of severity level and of functional status classification that are used when the results of the transient tests are interpreted, and it explains the relationship between this series and the international EMC standards of the IEC 61000-4 series.