What Is macOS? Apple’s Modern Operating System Explained



What is macOS? Great question! The Mac’s operating system has a long history. Here’s what you need to understand…


If you’re wondering “what is macOS?” You’ve come to the right place. In this explainer, we give a brief history of the Mac’s operating system and look at where it might be going next.

But first, understand that there have been three main eras of the Mac’s operating system. Those eras are:

  • The Mac OS era
  • The Mac OS X era
  • The macOS era

Those names (especially the first and third) are a big confusing, right? Not to worry, here’s what you need to know…

What Is macOS? Apple’s Modern Operating System Explained
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What Is macOS? The Mac OS Era

Apple is often credited with inventing the modern desktop operating system. That is, the operating system that uses a mouse and cursor to navigate around clickable items on a screen.

Apple unveiled it’s first such operating system in 1984 with the introduction of the Macintosh computer.

That operating system was called “Mac OS” and that operating system generation was in use for almost twenty years.

Mac OS introduced windowed computing, as well as operating stables like a file hierarchy and a trash can for deleting files. Mac OS was also the platform that third-party apps could run on.

While archaic looking by today’s standards, Mac OS was northing short of revolutionary in its time. Without Mac OS we very likely wouldn’t have the Windows operating system as we know it, and of course without Mac OS, we wouldn’t have today’s macOS nor would we have other operating systems like iOS.

Mac OS ran from version 1.0 in 1984 to version 9.2.2 in 2001.

What Is macOS? The Mac OS X Era

Mac OS was sunsetted in 2001 after Apple introduced its next-generation operating system called Mac OS X (Mac operating system 10). It’s also known as, simply, OS X. Mac OS X is the basis for the macOS we all use today.

At the time of its debut in 2001, Mac OS X was a UI marvel. It introduced the now-ubiquitous Dock application launcher, which is still used in macOS as well as iOS and iPadOS.

At the time of Mac OS X 10.0’s debut (the first version of Mac OS X), computer aficionados went crazy for its “Aqua” interface – the interface that introduced the red, yellow, and green window buttons still in use today. But back in Mac OS X, the Aqua interface meant that the buttons (and all Mac OS X interface elements took on a more three-dimensional, shiny look.

Mac OS X also introduced stables of the current Mac operating system like the Mac App Store and the iWork suite of productivity apps, including Pages, Numbers, and Keynote. Mac OS X was also the first Mac operating system generation to debut the iLife app suite, which included iMovie, iPhoto, iDVD, and more. It also introduced easy ways to uninstall apps.

Mac OS X was the branding Apple used from version 10.0 in 2001 to version 10.7 in 2011. Beginning with version 10.8, Apple rebranded Mac OS X to, simply, OS X. The OS X branding lasted from version 10.8 in 2012 to version 10.11 in 2015.

But in 2016, Apple launched the next era of the Mac’s operating system: macOS.

What Is macOS? The macOS Era

In 2016, Apple returned to a somewhat familiar branding. The company changed the Mac’s operating system’s name to “macOS” with the release of macOS 10.12 in 2016. That’s also the year Apple started branding macOS no by its version number, but by its nickname.

The following nicknames have been used for macOS:

The new macOS era has so far concentrated on bringing feature parity between Apple’s flagship iPhone operating system – iOS – and macOS. For example, in macOS Ventura, Apple’s has introduced Mac app versions of iPhone app stables like the Weather and Clock apps.

Handoff technology also allows tasks to be begun on the iPhone and carried over to the Mac, or vice versa. Also know that if you buy a modern Mac, that is, an Apple Silicon Mac, know that macOS is the only version of the Mac’s operating system that’s ever run on it.

Where the Mac’s operating system goes next is anyone’s guess…

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Michael Grothaus

Apple expert and novelist, Michael Grothaus has been covering tech on KnowYourMobile for the best part of 10 years. Prior to this, he worked at Apple. And before that, he was a film journalist. Michael is a published author; his book Epiphany Jones was voted as one of the best novels about Hollywood by Entertainment Weekly. Michael is also a writer at other publications including VICE and Fast Company.
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