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 attention is paid to high energy electron-positron experiments at PEP and PETRA leading to the most precise value of the Weinberg angle so far made from such experiments. Latest results from the high-statistics deep-inelastic neutrino scattering experiments have been included along with recent measurements of neutrino electron scattering, data and analysis for polarized-electron nucleon scattering, polarized-muon scattering, atomic parity violation and proton-antiproton experiments establishing the nature of the intermediate bosons.