This article reviews some of the experimental work on the Josephson effects. These effectsoccur in both superconductivity and superfluidity. In superconductivity they are found when two superconductors are separated by a thin insulating barrier (∼ 10−9m thick), or connected by a weak link of metal. A supercurrent can flow between the superconductors, and electromagnetic and magnetic fields can interact with this supercurrent. The interactions demonstrate quantum effects in a particularly striking way, have led to a better understanding of the superconducting state, and have also found some interesting applications.