In this text the author gives a rather complete account of the available experimental information on neutral current reactions as predicted by the standard theory of electroweak interactions. The data, which range from atomic parity violation to the discovery of the W and Z bosons, impressively support the theory as formulated by Glashow, Weinberg and Salam. The experimental data are critically reviewed and related to the standard theory, whose formal essentials are presented in a transparent way. A complete compilation is given of precision measurements of the Weinberg angle. Special...