MacOS

Apple Mac OS X is the operating system for Apple Macintosh computers, first released to the public on March 24, 2001. It is the successor to Mac OS 9, hence the X signifying both its Unix roots and the major release version number 10. As mentioned by Apple, Wikipedia, and others, it is said as Mac OS 10. It shares none of the "Classic" Mac OS design, and is completely rewritten and uses Next frameworks, a hybrid XNU/Mach kernel, and a BSD subsystem dubbed "Darwin". While underlying components of OS X are free/open source software, the top layers, such as the Aqua UI, are proprietary; Darwin packages can be downloaded and compiled from the Apple Open Source website to make a bootable OS.

Mac OS X has been built for three different architectures and four platforms during its release cycle to date. The first six releases (10.0.0-10.5.8) were designed for the PowerPC architecture, adding 64-bit PowerPC support as an additional platform for the G5 in 10.3 Panther. Intel (x86) support started with 10.4.4 Tiger, and was built as a universal release for both PowerPC/x86 with 10.5 Leopard, which finally dropped all G3 support. Since 10.6, PowerPC support is non-existent/dropped, and Mac OS X is currently designed for Mac computers with Intel 32-bit (x86) and Intel 64-bit (x86_64) architectures. AMD is not currently officially supported. Starting with 10.7 "Lion", Mac OS X is now referred to simply as "OS X".

The "iPhone OS" or iOS, which powers the iPhone, iPod touch, and iPad is a direct descendant of OS X, and shares its design and many internal frameworks. The latest version of OS X is "Yosemite" (10.10), released on October 16, 2014.

Versions

Mac OS X versions
Trade name	Version	Codename	Additional information
Mac OS X Developer Preview
Mac OS X Public Beta
Mac OS X Cheetah	10.0
Mac OS X Puma	10.1
Mac OS X Jaguar	10.2
Mac OS X Panther	10.3
Mac OS X Tiger	10.4
Mac OS X Leopard	10.5
Mac OS X Snow Leopard	10.6
Mac OS X Lion	10.7
Mac OS X Mountain Lion	10.8
Mac OS X Mavericks	10.9
Mac OS X Yosemite	10.10