[en] The aim of the Joint European Torus (JET) now under construction is to extend the study of magnetically confined plasma to conditions similar to those needed in a power-producing fusion reactor. To start with hydrogen and deuterium plasmas will be studied and later deuterium-tritium plasmas. The basic features of a Tokamak are described. The JET design uses, as far as possible, established manufacturing techniques and modular construction. The main parameters of JET are given and machine components described. The electrical supply system is also outlined. The JET buildings are due for completion in 1981 and it is hoped that JET will be installed, tested and ready for initial experimental works in 1983. (U.K.)