Mac OS X Lion, or Mac OS X 10.7, is the eighth major release of the Mac OS X operating system released on 20 July 2011. It was announced on 20 October 2010 at Apple's Back to the Mac event. This version dropped support for the x86 userland and architecture and removed Rosetta and Front Row. It introduced the Launchpad and was originally only released as an App Store update that could only be updated normally from Snow Leopard.
It is the first version of Mac OS X to not be distributed on optical discs as it was released as an online-only download through the Mac App Store. Although, Apple would later release a USB flash drive containing the installation image in August 2011.
It is the last version to be released under the Mac OS X name as the operating system's branding was shortened to OS X starting with the release of OS X Mountain Lion in 2012. It is also the last version of Mac OS X to be released under the old release schedule in which every version of Mac OS X was released every two years as the operating system shifted to a new annual update schedule starting with the aforementioned version.
The Launchpad has been added, which is an application launcher and organizer that features a design similar to the iOS home screen.
Mission Control has been added, which combines Exposé, Dashboard, and Spaces into a single view. The Dashboard is now in its own space, but can be returned to the previous view in System Preferences.
AirDrop has been added, which allows two Macs running Mac OS X Lion to send and receive files wirelessly via Wi-Fi.
Auto Save has been added. It allows compatible applications to automatically save the current document.
The ability to save and browse past versions of documents for applications in a Time Machine-like UI has been added.
Save As has been replaced by the Duplicate and Revert actions in several applications.
The Resume feature allows for applications to be suspended and re-opened later.
Most elements of the Aqua UI (including buttons, progress bars and the metal finish of windows) have been redesigned.
Scrollbars have been updated to be less intrusive, similar to iOS.
Improvements have been made to window resizing.
New multi-touch gestures have been added for trackpads.
Version 10.7.2 added iCloud support, replacing the MobileMe service.
Native system-wide support for full-screen applications was added.
Several enhancements have been made to Finder.
FaceTime is now included as a built-in application.
Safari 5.1, which includes the WebKit2 rendering engine.
Major design changes have been made to Address Book and iCal, now resembling their iPad counterparts.
Exchange 2010 support has been added to the Mail app.
Yahoo! Messenger support has been added to iChat.
Front Row and iSync applications have been removed. In addition, Adobe Flash Player and JRE are no longer included by default.
The Rosetta compatibility layer for running PowerPC applications has been removed.
FileVault 2, which adds supports full disk encryption and external hard drives.
Remote Install Mac OS X has been removed in favor of the Recovery Partition.
The Recovery Partition is now installed alongside the rest of the OS.
Auto-correction was changed to have an iOS-like popup box.
Support for Emoji has been added.
Removed Welcome video due to being digital-download only due to bandwidth reasons