Pushing the limits of NGSs solely AO: GMCAO and beyond

For almost two decades significant improvements have been made in the area of efficient WaveFront sensing to compensate areas in the sky of larger size and with better achieved quality. This has been accomplished in several directions, some of them become possible because of the development of new technologies, because of the availability of new kind of telescopes or because of the introduction of new concepts. While one of the currently favorite scenarios involve the so called Global MCAO, I will try to review these efforts placing them in perspective.