Among the new features, Tiger introduced Spotlight, Dashboard, Smart Folders, updated Mail program with Smart Mailboxes, QuickTime 7, Safari 2, Automator, VoiceOver, Core Image and Core Video. As with Panther, certain older machines were no longer supported Tiger requires a Mac with a built-in FireWire port. Apple stated that Tiger contained more than 200 new features.

Mac OS X Tiger was released on April 29, 2005. Snow Leopard only supports machines with Intel CPUs, requires at least 1 GB of RAM, and drops default support for applications built for the PowerPC architecture (Rosetta can be installed as an additional component to retain support for PowerPC-only applications) An update introduced support for the Mac App Store, Apple's digital distribution platform for macOS applications and subsequent macOS upgrades. For most users, the most noticeable changes are these: the disk space that the operating system frees up after a clean installation compared to Mac OS X 10.5 Leopard, a more responsive Finder rewritten in Cocoa, faster Time Machine backups, more reliable and user friendly disk ejects, a more powerful version of the Preview application, as well as a faster Safari web browser. Rather than delivering big changes to the appearance and end user functionality like the previous releases of Mac OS X, the development of Snow Leopard was deliberately focused on 'under the hood' changes, increasing the performance, efficiency, and stability of the operating system. Mac OS X Snow Leopard was released on August 28, 2009, the last version to be available on disc.

Messages, an instant messaging software application, replaces iChat Notes is added, as an application separate from Mail, synching with its iOS counterpart through the iCloud service. Notification Center is added, providing an overview of alerts from applications. Mountain Lion also includes more Chinese features, including support for Baidu as an option for Safari search engine. Application pop-ups are now concentrated on the corner of the screen, and the Center itself is pulled from the right side of the screen. Notification Center, which makes its debut in Mountain Lion, is a desktop version similar to the one in iOS 5.0 and higher. It also includes support for storing iWork documents in iCloud. It incorporates some features seen in iOS 5, which include Game Center, support for iMessage in the new Messages messaging application, and Reminders as a to-do list app separate from iCal (which is renamed as Calendar, like the iOS app). OS X Mountain Lion was released on July 25, 2012.

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