Being the 6^th major release of Mac OS X, this version had a number of innovative new features introduced by Apple, such as Time Machine (the system stored all versions of a file in an internal or external hard drive), BootCamp (granting the ability to easily boot into a different operating system), Dictionary and Spaces (form of a virtual desktop machine). Released in Late 2007, Mac OS Leopard had two versions of the system for desktop users as well as a separate version for servers. The operating system was lightweight, requiring only 512 MB RAM and minimum 9 GB of internal memory for the Mac system to install it.