Mac OS X Leopard (version 10.5) is the sixth major release of macOS, Apple's desktop and server operating system for Macintosh computers.

According to Apple, Leopard contains over 300 changes and enhancements compared to its predecessor, Mac OS X Tiger,[9] covering core operating system components as well as included applications and developer tools.

Leopard introduces a significantly revised desktop, with a redesigned Dock, Stacks, a semitransparent menu bar, and an updated Finder that incorporates the Cover Flow visual navigation interface first seen in iTunes.

Rory Prior, on the ThinkMac blog, criticized a number of changes to Leopard's user interface, including the transparent menu bar and the new folder icons.

Leopard can be "hacked" (see below) to install on these G3 and pre-867 MHz G4 machines but the system may behave erratically and many of the programs, features, and functions may not work properly or at all.

[citation needed] Some ways of running Leopard on certain unsupported hardware, primarily PowerPC G4 computers with CPU speeds lower than the official requirement of 867 MHz, have been discovered.

While some of the earlier beta releases were made to run on some later G3 machines (mostly later 800–900 MHz iBooks), no success with the retail version has been officially reported on G3 Macs except for some later iMacs and "Pismo" PowerBook G3s with G4 processor upgrades installed.

However, more recently it has been reported[59][60] that with some more work and use of kernel extensions from XPostFacto, Tiger and beta builds of Leopard, the OS can be made to run on G4-upgraded Macs as old as the Power Macintosh 9500, despite the lack of AGP-based graphics.

While Leopard can be run on any Mac with a G4 or later processor, some functionality such as Front Row or Time Machine fails to work without a Quartz Extreme-capable graphics card, which many of the earlier G4s did not include in their factory specification.

It also includes a lenticular cover, making the X appear to float above a purple galaxy, somewhat resembling the default Leopard desktop wallpaper.

[64] Apple attributed these problems to an outdated version of an unsupported add-on extension called Application Enhancer (APE), from Unsanity which had been incompatible with Leopard.