The European Commission has published a report on the Joint European Torus (JET) entitled "Nuclear fusion. Energy for centuries to come". JET, the world's largest fusion experiment, is a joint undertaking between the twelve EC Member States, the European Commission plus Sweden and Switzerland. The essential aim of JET is to obtain and study a plasma in conditions and dimensions approaching those needed in a thermonuclear reactor. The report includes the following: - An introduction to nuclear fusion; - Conditions for a fusion reactor; - JET plasma heating and diagnostics; - JET objectives, achievements and results; - The future programme for JET; - JET and the European Fusion Programme; - The "Next Step" experimental device for improved long-term fusion reactor technology.