OS X Yosemite (/joʊˈsɛmɪti/ yoh-SEM-it-ee; version 10.10) is the eleventh major release of macOS, Apple Inc.'s desktop and server operating system for Macintosh computers.

[7] Other design changes include new icons, light and dark color schemes, and the replacement of Lucida Grande with Helvetica Neue as the default system typeface.

Many of Yosemite's new features focus on the theme of "continuity", increasing its integration with other Apple platforms and services such as iOS and iCloud.

[11] The Handoff functionality allows the operating system to integrate with iOS 8 devices over Bluetooth LE and Wi-Fi; users can place and answer phone calls using their iPhone as a conduit, send and receive text messages, activate personal hotspots, or load items being worked on in a mobile app (such as Mail drafts or Numbers spreadsheets) directly into their desktop equivalent.

However, holding the Option key (⌥) while clicking the zoom button or double-clicking on the window chrome continues to invoke the original behavior.

[21] There is a "dark mode" in System Preferences which makes the Dock and menu bar darker.

Beta testers are required to acknowledge the potential risks involved with prerelease software, and sign a non-disclosure agreement (NDA).

"[25] Macworld's review generally praised Yosemite for its design, but noted that it had found WiFi network issues and that Continuity had proved unreliable.

[28] Some users who upgraded to Yosemite complained that the Finder fails to show the contents of folders.

[29] Spotlight on Yosemite by default reports the user's current location (at the city level) and all their search queries to Apple and third parties.