Abstract: Controlled nuclear fusion through magnetic confinement is a promising energy resource for the world. The high confinement operation mode (H-mode) of Tokamaks may significantly reduce the scale and costs of next generation experimental devices and fusion demonstration reactors. The H-mode characteristics, realization conditions, and scientific and technological issues need to be investigated and addressed urgently, including the triggering mechanism and dependence of the threshold power on the plasma parameters, as well as the driving force and control or mitigation techniques for the edge localized mode, observed in the high confinement operation mode.