As one of the alternative sources of energy for the future, fusion power must demonstrate that it can be a safe, clean and economically attractive option in a diverse and competitive energy marketplace. Conceptual power-plant design studies for both magnetic– and inertial–confinement approaches allows one to translate commercial requirements into design features that must be met if fusion is to play a role in the world's energy mix. As a new technology in the energy marketplace, fusion must have advantages to offset the inherent technical risk of a new technology in order to be accepted. Fusion electricity should have a competitive cost and fusion power plants should achieve a high degree of availability and reliability. Realization of the full safety and environmental potential of fusion will help fusion to achieve a large advantage over other sources of electricity. Progress in the physics of the magnetic fusion power plant, technology and design is described for tokamaks and alternative magnetic–confinement systems. Recent research in this area shows that potential safety and environmental attributes of fusion can be realized by using low–activation material and care in design. The projected economic prospects show that fusion will be capital intensive and the trends are towards higher power density and higher–performance systems in order to enhance the economic competitiveness of fusion. In addition, alternative confinement approaches may offer substantial economic and operational benefits, although their physics basis is much less developed. Fusion power technologies are far less advanced than plasma technologies, since the latter have evolved in conjunction with large fusion experiments. And yet the design, material choices and performance of plasma–facing and nuclear components are the dominant factors in arriving at an attractive power plant. Fusion power technologies are reviewed, and the R and D needed will be assessed in the context of the world's existing programmes.