This volume gives an introduction to the concept of connectivity in the format. Concepts are explained in a general way; constructs, such as net, appear in italics throughout this volume. Whenever more detail is desired about a topic the italicized constructs should be consulted in the EDIF Reference Manual. The EDIF Reference Manual contains the official definition of the format and should always be taken as the authoritative source of information. Further application guides will be provided in later volumes of this series.