It may be confusing when online articles dealing with OS X refer to names rather than numbers. This is because Apple decided to use the names of big cats when naming their new Unix-based OS
and then switched to landmarks for the latest versions:
10.0 Cheetah Mar 2001
10.1 Puma Sep 2001
10.2 Jaguar Aug 2002
10.3 Panther Oct 2003
10.4 Tiger Apr 2005
10.5 Leopard Oct 2007
10.6 Snow Leopard Jun 2009
10.7 Lion Jul 2011
10.8 Mountain Lion Jul 2012
10.9 Mavericks Oct 2013
10.10 Yosemite Oct 2014
10.11 El Capitan Sep 2015
10.12 Sierra Sep 2016
10.13 High Sierra Sep 2017
10.14 Mojave Sep 2018
10.15 Catalina Oct 2019
11.0 Big Sur Late 2020
