With the termination of the physics program at PETRA, and with the start of TRISTAN and the SLC and later LEP, an era of e+e- physics has come to an end and a new one begins. The field is changing from a field of few specialists, to becoming one of the mainstream efforts of the high energy community. It seems appropriate at this moment to summarize what has been learned over the past years, in a way most useful to any high energy physicists, in particular to newcomers in the e+e- field. This is the purpose of the book. This book should be used as a reference for future workers in the field of e+e- interactions. It includes the most relevant data, parametrizations, theoretical background, and a chapter on detectors.