VISAR predecessors are described, including the displacement and velocity interferometer techniques for shock instrumentation. The advance to the VISAR in 1972 made laser interferometry applicable to a very wide range of shockwave experiments. With a 1974 refinement of the VISAR data reduction equation, the VISAR was shown to produce velocity measurements with better than 1&percent; accuracy, and with time resolution to about 2 ns. The power of the VISAR was demonstrated in a plate impact study of the 13 GPa phase transition in iron. Rate effects in shock compressed iron were measured and correlated with theory, and the unloading stress-volume path was determined, revealing the reverse phase transition stress to unprecedented accuracy. Later improvements in VISARs are reviewed, including the lens delay VISAR (Amery), the push-pull VISAR (Hemsing), the ORVIS (Bloomquist and Sheffield), the line VISAR (Hemsing), the fixed-cavity VISAR (Sweat, et al.), the “never-search-for-fringes” VISAR (Barker), and the multi-beam VISAR (Barker). ©2000 American Institute of Physics.