Apple computers run macOS, their own operating system built specifically for Mac hardware

macOS is the operating system that powers all Apple desktop and laptop computers. It is not Windows, not Linux, and not Android — it is built by Apple for Apple machines only. Every Mac you buy comes with macOS already installed, and Apple releases a new version roughly once a year.

The operating system handles everything your Mac does behind the scenes: managing files, running programs, connecting to the internet, and controlling hardware like your screen, keyboard, and trackpad. You interact with it through the desktop, the Dock (the bar at the bottom of your screen), and the menu bar at the top.

Key Takeaways

  • macOS is Apple's proprietary operating system and runs only on Mac computers, not on PCs or other devices.
  • Apple releases a new macOS version each year, usually in the fall, and older Macs may not support the newest versions.
  • macOS is based on Unix, a stable operating system foundation used in servers and professional systems worldwide.
  • You cannot install macOS on a non-Apple computer, and you cannot install Windows or Linux as the main operating system on most modern Macs without specialized tools.

How macOS versions are named and numbered

Until 2020, Apple named macOS versions after California locations: Mojave, Catalina, Big Sur. Starting with macOS 11, Apple switched to numbering: macOS 12 (Monterey), macOS 13 (Ventura), macOS 14 (Sonoma), and macOS 15 (Sequoia). The number tells you roughly how recent the version is, though the California names are still used informally.

Each Mac model has a maximum macOS version it can run. A Mac from 2015 might max out at macOS 12, while a 2020 Mac can run the current version. Apple stops releasing security updates for versions older than the current one and the previous one, so running an old macOS leaves your computer vulnerable to known security problems.

What makes macOS different from Windows

macOS and Windows are completely separate operating systems built by different companies on different foundations. Windows runs on computers from Dell, HP, Lenovo, and many others. macOS runs only on Macs. They look different, work differently, and run different programs.

A program written for Windows will not run on macOS without modification. Microsoft Office exists for both, but a game built for Windows will not work on a Mac. This is why some people choose Mac — the limited software selection means fewer viruses and malware designed for that platform — and why others avoid Mac, because their specific software may not exist for it.

The Unix foundation under macOS

macOS is built on Unix, an operating system architecture that has been refined for decades and powers servers, supercomputers, and professional workstations. This foundation makes macOS stable and reliable for people who need their computer to work without crashing.

Because of this Unix base, macOS includes a command line (called Terminal) that lets advanced users type commands directly instead of clicking. Most Mac users never open Terminal, but professionals and developers use it regularly. This same Unix foundation is also why Linux and macOS share some similarities, even though they are separate systems.

Can you run other operating systems on a Mac

You cannot install Windows or Linux as the main operating system on most modern Macs the way you can on a regular PC. Apple's hardware and software are tightly integrated, and newer Macs use Apple's own processors (the M1, M2, M3 chips) that Windows does not officially support.

Some older Intel-based Macs can run Windows through specialized software like Parallels Desktop or Boot Camp, but this is complicated and not officially supported by Apple. For most people, if you need Windows software, you should buy a Windows PC instead of trying to force it onto a Mac.

How to check which macOS version your Mac is running

Click the Apple menu in the top-left corner of your screen, then select "About This Mac." The window that opens shows your macOS version number and name. You can also see how much storage your Mac has, how much memory (RAM) it has, and which processor it uses.

If you want to update to a newer macOS version, go to System Settings (or System Preferences on older Macs), find the Software Update section, and click "Check Now." If your Mac is may be able to access for a newer version, you will see the option to read and install it. Updates usually take 30 minutes to an hour and require a restart.

Why Apple controls both the hardware and software

Apple designs the Mac hardware and writes macOS specifically for that hardware. This is different from Windows, where Microsoft writes the operating system and other companies build the computers. Because Apple controls both sides, macOS can be optimized for Mac hardware in ways Windows cannot be for the hundreds of different PC models it runs on.

This also means Apple decides when to stop supporting older Macs. A Mac from 2013 might not be able to run the current macOS, even if the hardware could theoretically handle it. This is by design — Apple wants to push users toward newer machines — and it is one reason some people prefer Windows PCs, which can often run the latest Windows version on older hardware.

Frequently Asked Questions

Is macOS the same as iOS?

No. iOS runs on iPhones and iPads. macOS runs on Macs. They share some code and design ideas, but they are separate operating systems. You cannot run iOS on a Mac or macOS on an iPhone.

Do I need to pay for macOS updates?

No. macOS updates are free. When a new version is released, you can read and install it at no cost. This is different from older versions of Windows, which required a paid license.

What happens if I do not update macOS?

Your Mac will continue to work, but it will become less find over time. Apple stops releasing security patches for old versions, so hackers can exploit known problems. If you use your Mac for banking or shopping, running an outdated macOS puts your accounts at risk.

Can I downgrade from a newer macOS to an older one?

Downgrading is possible but difficult and requires erasing your Mac and reinstalling the older system from scratch. Most people do not do this. If you upgrade and regret it, you are usually stuck with the new version.

Why do some programs not work on my Mac?

The program was likely built for Windows only, or it was built for an older macOS version that your Mac no longer runs. Check the software maker's website to see which operating systems they support. If they do not list macOS, that program will not work on your computer.