An account is given of the high performance plasmas established by development of the H-mode regime in JET in the experimental campaigns up to 1992. High performance in this case is measured in terms of the confinement enhancement achieved over the L-mode scaling as measured using the plasma diamagnetism. Three JET H-mode regimes have achieved enhancement factors (HGDIA) over Goldston L-mode scaling of 2.5<HGDIA<4.0. These are the Pellet Enhanced Performance (PEP) H-mode, the high bootstrap fraction (high beta POL) H-mode and the Hot Ion (HI) H-mode. The phenomenology of these three regimes is reviewed and contrasts and common threads are elucidated. All the regimes are transient (on a resistive diffusion timescale) and the mechanisms terminating the period of enhanced confinement are discussed. Common features between the high beta POL and HI regimes are identified which suggest that they are effectively two aspects of a unified Very High (VH) confinement regime. The experimental conditions for accessing this regime are reviewed.