[en] Fusion energy is a very promising alternative to the future energy demand. Unlimited fuel resources, practical emission and waste free energy production with high power density are advantages which are not obtainable in any other energy system. Research in controlled thermonuclear fusion started already forty years ago. The progress has been rapid after the first tokamak experiments in the late sixties. The scientific feasibility of fusion energy is recently demonstrated with large tokamaks by creating the extreme plasma conditions - high temperature and confinement - which are needed for fusion reactions. There are, however, difficult technological problems to be solved in the next generation tokamak reactors such as the International Thermonuclear Experimental Reactor - ITER. These machines are under design, and the experimental programme is expected to start a few years after the year 2000. Experiments will take well over ten years so that the full-scale demonstration power plants are not likely to operate before 2020. This means that fusion is not a timely answer, but in long term, fusion energy has an excellent potential to be the final and sustained solution to the energy needs of mankind