MacOS

2001–2002


This logo was used for the Mac OS X v10.0, code named "Cheetah", and v10.1, code named "Puma". These versions were preceded by the Mac OS X Public Beta, code named "Kodiak". This version was made for software developers to be able to create their software so it was ready for the release of v10.0. Cheetah and Puma were the first major releases of the operating system, and were branded with a thin, light blue "X" representing the brand. Following v10.0 and v10.1, Mac OS X v10.2 was released with a rebranded logo.

2002–2003


In 2002, Mac OS X v10.2, code named "Jaguar", was released with a brand new logo. The logo was an "X" that had a jaguar print instead of the previous blue "X". This was the first release of Mac OS X in which the OS was actually marketed using the code name, Jaguar. Following v10.2, Mac OS X Panther was released in 2003.

2003–2005


Mac OS X Panther was released in 2003, with the logo redesigned into a thick, gray "X". Panther was followed by Tiger in 2005.

2005–2007


Mac OS X Tiger was released in 2005, with the "X" transformed into a metallic, bright "X". The operating system included many new features and became the best-selling system in comparison to its predecessors. In 2007, Leopard was released to follow Tiger.

2007–2011


In 2007, Mac OS X Leopard was released. The logo was redesigned into a glistening, black "X". The Leopard system also brought a major redesign to the interface itself. Following Leopard, Mac OS X Snow Leopard was released in 2009. There were no changes made to the logo until the next system, Lion. The primary reason for this is that Snow Leopard was intended to be a refined and more efficient version of Leopard instead of a complete redesign of the system's interface or features.

2011–2012


Mac OS X Lion was released in 2011, with the classic "X" being abandoned in this release. The logo was instead replaced with a circle containing an image of a lion. Lion was intended to be only available from the Mac App Store, unlike previous operating systems. Following Lion, Mountain Lion was released only a year later.

2012–2013


OS X Mountain Lion was released in 2012, with a simple change from the previous logo. The lion in the previous logo was replaced with a mountain lion. The system was dubbed "Mountain Lion" to signify its purpose as a refinement from Lion. Along with that, Mountain Lion was also made to enable better synchronization between iOS devices and OS X. Mountain Lion is succeded by 10.9 Mavericks which followed a year later..

2013–present


OS X 10.9 Mavericks was annouced at WWDC on June 10, 2013 with the X returning in this version along with some green and blue inside it, and new features are available in this version. It is expected to come out in the fall, in which it will be the current version after Mountain Lion.