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Screen (Dashboard) – General appearance unchanged 2001
OSX 10.0 Cheetah

Mac OS X and macOS version names

OS X 10 beta: Kodiak
OS X 10.0: Cheetah 2001
OS X 10.1: Puma 2001
OS X 10.2: Jaguar 2002
OS X 10.3 Panther 2003
OS X 10.4 Tiger 2005
OS X 10.5 Leopard 2007
OS X 10.6 Snow Leopard 2008
OS X 10.7 Lion 2011
OS X 10.8 Mountain Lion 2012
OS X 10.9 Mavericks 2913
OS X 10.10: Yosemite 2014
OS X 10.11: El Capitan 2015
macOS 10.12: Sierra 2016
macOS 10.13: High Sierra 2017

Only the latest version, High Sierra, can be downloaded from the App Store

Take a look at your version: Apple Logo > About this Mac > More info > Storage