vSphere 6.5 is VMwares 6th generation of bare-metal enterprise virtualization software, from ESX1.x (2001/2), 2.x (2003) to Virtual Infrastructure 3 (2006), in May 2009 to vSphere 4.x. The ESXi architecture (small-footprint) became available in Dec 2007. vSphere 5 was announced July 2011 with GA August 2011 and was the first vSphere release converged on ESXi only, vSphere 5.1 was released 10th Sep 2012, vSphere 5.5 on Sep 22nd 2013, vSphere 6 on Feb 2nd 2015, vSphere 6.5 on November 15th 2016