Stellarators are "generators of stellar energy," and their principle was discovered before tokamaks. A helical-twisted magnetic field, necessary for successful plasma confinement, is generated only by magnetic coils of various shapes. The stellarator is a device capable of continual work, which is an important feature for a power plant. However, stellarators experienced a boom only recently, when sufficient computational power for creating desired magnetic coil shapes became available. There are over ten stellarators operating around the world. The largest are the Wendelstein 7-X in Germany, the Large Helical Device in Japan, and the Helically Symmetric eXperiment in the USA.