Radio Frequency techniques have been widely used for heating and current drive in fusion plasma physics experiments and are sufficiently mature to be presently considered for use in ITER. Their progress has followed closely theoretical predictions, understanding as well as technical progress. In early experiments the limitations were on the physics while in more recent experiments, the technical aspect has played a more important role and in some cases was the limiting factor, the increasing size of tokamaks and other fusion devices requiring more powerful RF systems.