Use for questions referring specifically to versions of OS X 10.7, Lion. Non-version-specific questions related to OS X should be tagged with [osx]. Questions about Mac hardware should be tagged with [mac]. Questions about running OS X on non-Apple hardware are generally considered off-topic.
OS X (pronounced OS ten; "X" is a Roman numeral), version 10.7, codenamed Lion, is the 8th major release of Apple's Mac operating system. It was released on July 20th, 2011. It is a Unix-based graphical interface operating system.
Lion runs on Intel-based Macs and is the first OS X released only in a 64 bit version. Lion and subsequent OS X versions do not support Rosetta (software that allowed many PowerPC applications to run on Intel-based Macs without modification).