Apple’s macOS is the operating system that runs on the company’s Mac lineup. The software, which is free to update for all Mac and MacBook owners, handles system funtions, applications, and hardware controls. 

macOS is Apple’s desktop operating system

Apple designed macOS to run as optimally as possible on the company’s hardware. It also connects to Apple’s online services, including the Mac App Store, Apple Music, iCloud, and other services. It includes considerable security protections to keep users and their data safe from harm.

Based on Unix at its core, macOS is a flexible operating system. Power users will appreciate its configurable aspects, such as via Terminal commands or server-based applications. However, it’s also friendly towards more casual users, gaining many iOS features and visual design cues through the years. 

macOS Name Changes

macOS started as Mac OS, which was launched in 1984. It underwent multiple major releases until its final version, Mac OS 9, shipped in 1999.

Apple changed its policy with the launch of Mac OS X, colloquially known as OS X, in March 2001. After that release, Apple kept the major version number at 10 for nearly two decades. Instead of changing the major version number, Apple used a following minor number to indicate annual upgrade releases, such as version 10.1, 10.2, and 10.3.

That changed with macOS Big Sur’s arrival in 2020. Apple finally retired the 10.X naming scheme and called Big Sur version 11.

In 2016, Apple altered how it referred to the operating system. Still known as Mac OS or OS X prior to that, the company switched  to macOS. This matched the naming pattern of its other operating systems, including iOS, tvOS, and watchOS.

As well as the official name and version number, Apple has also altered the release title for each over time. From the release of Mac OS X 10.0 Cheetah until OS X 10.8 Mountain Lion, Apple referred to the operating system by the name of a big cat. Starting with OS X 10.9 Mavericks, Apple switched the naming convention to refer to places in California. The company has continued to do so since then.

macOS Releases

macOS 11 Big Sur

macOS Big Sur

Apple announced macOS Big Sur at WWDC 2020 and released the new OS in November. The operating system was redesigned with new textured icons, colorful sidebars, and more transparent and curvy elements. The design changes make the Mac look much closer to iPadOS than ever before.

Big Sur also begins to move the Mac away from Intel chips to custom Apple Silicon, including the new M1 chip.

Apple offers several tools to help developers make the transition. All iOS and iPadOS apps can run natively on Apple Silicon, though developers can opt out of offering them in the Mac App Store. They can also easily upgrade their mobile apps to be more Mac-like with Mac Catalyst. The new Mac computers, including updated models of the 13-inch MacBook Pro, MacBook Air, and Mac mini, run Rosetta 2. This virtualization software can helps users and developers transition away from their Intel apps.

Apple updated Safari in the new version with more privacy and security protections. Apple has made third-party extensions work with Safari even if they were built for Chrome. The ability to translate webpages is now a built-in function and works entirely on-device.

Messages is now a Mac Catalyst app that has feature parity with its iOS counterpart. Users can send message effects, Tapbacks, and tag users in a group chat just like in iOS 14 for iPhone.

macOS 10.15 Catalina

macOS Catalina brought Catalyst and Sidecar to the OS

A major change in Catalina was Apple’s decision to end support for 32-bit apps, requiring developers to rework their apps into 64-bit versions to continue functioning properly. Not all developers elected to migrate their apps, forcing some users to choose between abandoning vintage apps or upgrading to Catalina.

Another chief change is the removal of iTunes, in favor of new apps that replace the majority of its functions. New apps for Apple Music, Apple Podcasts, and Apple TV offer the core functions of iTunes. iOS device backup duties, another iTunes mainstay, found a new home in the Finder. 

10.15.1 introduced new emoji, support for the AirPods Pro, AMD Navi RDNA graphics cards in eGPU enclosures, alteration to the Photos app, and an option to opt in to Siri reviews. 

10.15.2 made refinements to the Apple News, Stocks, Photos, Mail, and other apps, as well as fixes for issues in the Photos and Mail apps. 

10.15.3 improved multi-stream video editing performance for HEVC and H.264-encoded video on the 16-inch MacBook Pro, along with Pro Display XDR optimizations. 

10.15.4 added improved support for HDR-compatible monitors and added reference modes for the Pro Display XDR. 

macOS 10.14 Mojave

Day and night mode change your app appearance

Out on September 24, 2018, macOS 10.14 Mojave’s main new feature was dark mode, an alternate user interface. Users can switch between dark and light modes, and the theme can also change on a schedule via Dynamic Desktop. 

Apple ported several iOS apps to macOS, including a News app, Stocks, Voice Memos, and Home for managing HomeKit. The initiative was part of “Project Marzipan,” to enable iOS-developed apps to function in macOS with few changes. This initial quartet of apps demonstrated the concept to users and developers.

On the desktop, Stacks are an organization method for files in the workspace. Stacks piles up similar files into grouped collections automatically. Continuity Camera allows for photographs taken on an iPhone to be instantly transferred to within an application on macOS. 

10.14.4 added integration with the just-launched Apple News+ subscription service, in the Apple News app. Support for second-generation AirPods, Safari Autofill for MacBooks with Touch ID hardware, air quality index readings in Maps, and real-time text for phone calls made through a nearby iPhone were among the other changes. 

10.14.5 was largely a maintenance update, though included fixes relating to AirPlay 2 support. 10.14.6 continued the security and bug fix theme. 

macOS 10.13 High Sierra

The naming scheme took a half-step despite major underlying changes to the OS

Released on September 9, 2017, macOS 10.13 High Sierra included a major change for storage, with macOS switching over to the Apple File System, APFS. Intended to take advantage of the use of Flash and SSD storage, Apple built AFPS with encryption and enhanced security in mind. The company designed it to work with all Apple platforms, including watchOS, iOS, tvOS, and macOS. 

The addition of Metal 2 included driver optimizations that brought up to 10 times better draw call throughput for graphics work, more debugging tools, and a migrated Mac Window Server.

Other notable items include the migration of H.264 to H.265/HEVC to better work with 4K and HDR content. It added faster and more power-efficient Safari. Apple’s browser also added increased privacy protection, including Intelligent Tracking Prevention. 

High Sierra was the last version to support 32-bit apps “without compromises,” with Apple continuing its push to get developers over to making 64-bit apps.

10.13.1 added 70 new emoji, a fix to a Bluetooth bug involving Apple Pay, reliability improvements to Microsoft Exchange message encryption, a Spotlight input fix, and the patching of assorted KRACK wi-fi vulnerabilities. 

10.13.2 was largely a maintenance release, improving compatibility for some USB audio devices, VoiceOver navigation while viewing PDFs, and a fix for a Root account generation flaw. 

10.13.3 included relatively small updates, including an issue where Messages conversations were temporarily stored out of order. 

10.13.4 incorporated a warning to users if they are running 32-bit apps and the launch of official eGPU support. 

10.13.5 added support for Messages in iCloud, allowing conversations to be synchronized between multiple Apple devices. 

10.13.6 delivered support for AirPlay 2, along with a variety of stability and security improvements. 

macOS 10.12 Sierra

The OS that Apple changed the name from Mac OS X to macOS

Available to end users on September 20, 2016, macOS 10.12 Sierra heralded the introduction of Siri on Mac, bringing Apple’s digital assistant to the desktop. Sierra also added a cross-platform clipboard synchronization with iOS and iCloud file synchronization between iOS and macOS.

The update added Picture in Picture feature, familiar to iOS users. It also included rich Messages on par with iOS, changes to Photos, Apple Pay for the web, and auto-unlock via Apple Watch. 

10.12.1 added iPhone 7 Photos compatibility fixes, Safari security enhancements, and fixes to Microsoft Office and Exchange issues, among other changes. 

10.12.2 improved the setup and reliability of Auto Unlock, Touch Bar screenshot support, and a wide variety of fixes and improvements. 

10.12.3 improved automatic graphics switching on the 2016 MacBook Pro 15-inch, a fix for PDF corruption, and MacBook Pro battery drain issues in Safari. 

10.12.4 added Night Shift, new PDFKit APIs, cricket scores to Siri, and more options for iCloud Analytics. 

10.12.5 solved stuttering audio issues for USB headphones, a “media-free” installation of the Windows 10 Creators Update using Boot Camp, and enhancements to the Mac App Store for compatibility with “future software updates.”

10.12.6 largely consisted of a maintenance update.