Rudimentary catalogues of cosmic voids were first complied in the mid-1980s, but they were limited in scope by the lack of adequate deep galaxy survey data. Over several decades, catalogues have improved as have cosmic void identification methods. Voids in the galaxy distribution have become important objects and modern tools that are now used to investigate properties of the Universe. They have been and continue to be applied to problems in precision cosmology. The first step in utilizing this new tool is to compile massive surveys of the distant Universe that yield sufficiently large samples of cosmic voids. Then reliable void identification techniques were developed. These include sophisticated methods of 3D analysis. For some tests, “stacked voids” are created to enhance the measurement precision. Specific research results are summarized showing concrete results. Three other topics are discussed: topology of the void and supercluster structure, the LTB Universe models, and finally void galaxies.