Work aimed at compiling detailed catalogs of variable stars in the Galaxy, which has been carried out continuously by Moscow variable-star researchers since 1946 on behalf of the International Astronomical Union, has entered the stage of the publication of the 5th, completely electronic edition of the General Catalog of Variable Stars (GCVS). The GCVS 5.1 is freely accessible on the Internet. The authors recommend citing their paper as a unified reference to the 5th edition of the GCVS. The GCVS is the only reference source on all known variable stars. This version contains the electronically-readable version as distributed by the Sternberg Astronomical Institute and Institute of Astronomy (Russian Acad. Sci.), Moscow. After the publication of Volume III of the 4th edition of the GCVS, the subsequent Name-lists with numbers from 67 to 77 contained only names of variable stars in the GCVS systems, together with their coordinates and variability types. The authors actually started compiling the 5th edition of the GCVS ten years ago, with the 78th Name-list of Variable Stars, which provided (as did all subsequent Name-lists) complete GCVS information for each star (in addition to the variability types, ranges of brightness variations, epochs of brightness maxima or minima, periods, etc.). In all, the 78th-81st Name-lists contain more than 13300 variable stars. The complete revision of information on the coordinates of variable stars (see the Introduction section of the reference paper) was also a part of the transition to the 5th edition. The present electronic version of the GCVS5.1 is available from Sternberg Astronomical Institute (Lomonosov Moscow University) and Institute of Astronomy (Russian Academy of Sciences) at <a href="http://www.sai.msu.su/gcvs/gcvs/">http://www.sai.msu.su/gcvs/gcvs/</a>; as a first release of the fifth GCVS edition. Information on the contents and principles of the fifth edition can be found in Samus et al. (2017), the official reference to GCVS 5.1. The GCVS 5.1 version contains data for individual variable objects discovered and named as variable stars by 2021 and located mainly in the Milky Way galaxy. The total number of named variable stars, not counting designated non-existing stars or stars subsequently identified with earlier-named variables, is now 58035. The stars of the GCVS 5.1 are stars of the GCVS fourth edition plus Name-lists Nos. 67-84. The stars from the Name-lists Nos.78-84 are presented in the complete GCVS format. Complete information for stars of the Name-lists Nos. 67-77 is so far provided in the first 20 constellations (Andromeda to Cepheus). In these constellations, the GCVS information has been completely revised with active use of new publications as well as observations retrieved by the GCVS compilers by data mining and used to determine new variability types and new light elements whenever possible. The authors are continuing this work and will introduce new data for the next constellations as soon as they are ready. This version of the GCVS catalog was last updated by the HEASARC in September 2022, based on the file at <a href="http://www.sai.msu.su/gcvs/gcvs/gcvs5/gcvs5.txt">http://www.sai.msu.su/gcvs/gcvs/gcvs5/gcvs5.txt</a>;. This is a service provided by NASA HEASARC .