50 years of success for SRF accelerators—a review

The past five decades have seen many successes in superconducting radio-frequency (SRF) enabling a variety of accelerators. These successes are the result of steady progress in understanding the science behind the performance limitations, and in developing effective countermeasures to advance key performance aspects. SRF technology has developed in parallel to bring major accelerators to reality for a wide variety of fields from high energy physics, nuclear physics, and nuclear astro-physics to materials science. (topical review)