A review is given of the present state of research into the physics of quasistationary confinement of hightemperature plasmas in magnetic fields. Both closed (toroidal) and open magnetic traps are considered. A major part of the review is devoted to the physics of plasma confinement in tokamaks. A brief account is given of the fundamentals of the tokamak, as well as of the problems of equilibrium, stability, cross-field heat and particle transport, and plasma heating and maintenance of current. The stellarator and the reversed-field pinch are also considered. The current status of open traps is reviewed.