There have been 16 versions of Ruby on Rails between 2005 and 2019, with the first version (version 1.0 coming out December 13, 2005, and the most recent version in that year span (version 6.0) coming out on August 16, 2019.
Old version, no longer maintained: 1.0 December 13, 2005 Current stable version: 6.0 August 16, 2019 Old version, no longer maintained: 1.2 January 19, 2007 June 1, 2008 December 7, 2007 November 21, 2008 August 29, 2010 March 16, 2009 August 31, 2011 January 20, 2012 June 25, 2013 April 8, 2014 December 19, 2014 June 30, 2016 May 10, 2017 April 9, 2018 Older version, yet still maintained: 5.2 Old version, no longer maintained: 5.1 Old version, no longer maintained: 5.0 Old version, no longer maintained: 4.2 Old version, no longer maintained: 4.0 Old version, no longer maintained: 4.1 Old version, no longer maintained: 3.2 Old version, no longer maintained: 3.0 Old version, no longer maintained: 3.1 Old version, no longer maintained: 2.3 Old version, no longer maintained: 2.2 Old version, no longer maintained: 2.1 Old version, no longer maintained: 2.0 
