In nearly four years of operation of the JET tokamak, experiments have been undertaken with input powers up to 7MW of ICRF, 10MW beam and 18MW during combined operation. JET results show many advances made during this period. With ohmic heating alone, good confinement (tE up to 0.9s), high temperatures (Te up to 5keV) and a fusion product <ni, tE, Ti> = 1020m–3.s.keV have been achieved. Highly efficient ion heating has been observed (Ti>12.5 ±1.5keV) at moderate neutral beam injection levels (PNB- <8MW) and at low average densities (ni = 1–1.5 x 1019m–3). But with increasing additional heating, confinement is degraded and thus additional heating has little impact on the fusion product. However, a fusion product of 2 x 1020m–3.s.keV has been achieved with a magnetic separatrix configuration in JET. Experimental results are examined in terms of possible scaling laws for electron energy confinement and implications for a reactor are considered.