An overview of JET experimental results in DT plasmas directly relevant to ITER modes of operation are presented. Experiments in D:T mixtures varying from 100:0 to 10:90 and those carried out in hydrogen plasmas, show that the H-mode threshold power has approximately an inverse isotopic mass dependence. Matching some of the key dimensionless parameters to the ITER values, the ITER-similarity experiments with ITER shape and safety factor (q) show that the global energy confinement time is practically independent of isotopic mass (~A0.03±0.08) where A is the atomic mass of the hydrogenic species. Subtracting the edge pedestal energy (which scales as ~A0.57±0.2) from the total stored energy leads to a ~A-0.17±0.1 dependence of confinement in the plasma core, very similar to that expected from the gyro-Bohm transport (~A-0.2) model. The observed scaling of the edge pedestal energy is consistent with a model in which the edge pressure gradient saturates at the ballooning limit over a region of width that scales as the ion poloidal Larmor radius governed by the average energy of the fast-ions in the edge. The steady state total stored energy for a given input power in both ion cyclotron resonance heated (ICRH) and NBI discharges is the same despite the lower edge pedestal in the ICRH case which is compensated by a more peaked power deposition profiles in ICRH. ELM frequency is smaller with NBI; it decreases with isotopic mass both in NBI and ICRH discharges. A steady-state, type I ELMy H-mode discharge with ITER shape and q at 3.8T/3.8MA with an input power of 22 MW, produced a Q≈0.18 for 3.5s and extrapolates well to ignition with ITER parameters. Here, Q is the ratio of fusion output power to input power. The thermal ELMy H-mode confinement both in deuterium and tritium gas fueled plasmas decreases significantly when the plasma density exceeds 0.75 of the Greenwald (nGW) limit and the maximum density achieved is 0.85nGW. In L-mode, the density limit decreases with increasing isotopic mass roughly in accordance with code predictions. ITER reference ICRH scenarios have been evaluated. Second harmonic heating of tritium at densities available in JET produces strong tails and heats electrons predominantly as expected. He3-minority in 50:50 D:T and tritium dominated plasmas showed strong bulk ion heating leading to ion temperatures up to 13keV with ICRH alone. Deuterium minority ion cyclotron heating in tritium plasmas at a power level of 6MW produced a steady-state record values of Q≈0.22 for more than 2.5s.