OS X
X11.app was initially available as a downloadable public beta for Mac OS X 10.2 Jaguar and later included as a standard package for Mac OS X 10.3 Panther. In Mac OS X 10.4 Tiger X11.app was an optional install included on the install DVD. Mac OS X 10.5 Leopard, Mac OS X 10.6 Snow Leopard, and Mac OS X 10.7 Lion installed X11.app by default, but from OS X 10.8 Mountain Lion on Apple dropped dedicated support for X11.app, with users being directed to the open source XQuartz project (to which Apple contributes) instead.