The history of macOS, Apple's current Mac operating system originally named Mac OS X until 2012 and then OS X until 2016, began with the company's project to replace its 'classic' Mac OS.That system, up to and including its final release Mac OS 9, was a direct descendant of the operating system Apple had used in its Macintosh computers since their introduction in 1984.

• On September 20, 2016, Apple announced that macOS Sierra, the latest major release of the world’s most advanced desktop operating system, is now available as a free update. MacOS Sierra brings Siri to the Mac with intelligent and helpful features users know and love from the iPhone and iPad, along with all-new capabilities designed specifically for use on the desktop.
• Mac OS X 10.6 Snow Leopard. Mac OS X 10.5 Leopard. Get it for PowerPC or 32bit Intel. Mac OS X 10.4 Tiger. Mac OS X 10.4.7 or later is required. Get it for PowerPC or Intel. Mac OS X 10.3 Panther. QuickTime 6.5.2 or later is required. Get it for PowerPC.
• MacOS (originally named 'Mac OS X' until 2012 and then 'OS X' until 2016) is the current Mac operating system that officially succeeded the classic Mac OS in 2001. Although the system was originally marketed as simply 'version 10' of Mac OS, it has a history that is largely independent of the classic Mac OS. It is a Unix-based operating system built on NeXTSTEP and other technology developed.
• Hackintosh.com links to everything you need to build a Hackintosh and get macOS Big Sur (macOS 11) as well as many earlier versions of Mac OS X running on an unsupported computer - instructions, step-by-step 'how to' guides, and tutorials - in addition to installation videos, lists of compatible computers and parts, and communities for support.

On September 20, 2016, Apple announced that macOS Sierra , the latest major release of the world’s most advanced desktop operating system, is now available as a free update.

macOS Sierra brings Siri to the Mac with intelligent and helpful features users know and love from the iPhone and iPad, along with all-new capabilities designed specifically for use on the desktop.

Features like Universal Clipboard, iCloud Desktop and Documents, Auto Unlock and Apple Pay on the web help your Mac work even better with other Apple devices.

These advanced steps are primarily for system administrators and others who are familiar with the command line. You don't need a bootable installer to upgrade macOS or reinstall macOS, but it can be useful when you want to install on multiple computers without downloading the installer each time.

Download macOS

Find the appropriate download link in the upgrade instructions for each macOS version:

macOS Catalina, macOS Mojave, ormacOS High Sierra
Installers for each of these macOS versions download directly to your Applications folder as an app named Install macOS Catalina, Install macOS Mojave, or Install macOS High Sierra. If the installer opens after downloading, quit it without continuing installation. Important: To get the correct installer, download from a Mac that is using macOS Sierra 10.12.5 or later, or El Capitan 10.11.6. Enterprise administrators, please download from Apple, not a locally hosted software-update server.

OS X El Capitan
El Capitan downloads as a disk image. On a Mac that is compatible with El Capitan, open the disk image and run the installer within, named InstallMacOSX.pkg. It installs an app named Install OS X El Capitan into your Applications folder. You will create the bootable installer from this app, not from the disk image or .pkg installer.

Use the 'createinstallmedia' command in Terminal

1. Connect the USB flash drive or other volume that you're using for the bootable installer. Make sure that it has at least 12GB of available storage and is formatted as Mac OS Extended.
2. Open Terminal, which is in the Utilities folder of your Applications folder.
3. Type or paste one of the following commands in Terminal. These assume that the installer is still in your Applications folder, and MyVolume is the name of the USB flash drive or other volume you're using. If it has a different name, replace MyVolume in these commands with the name of your volume.
   Catalina:*
   Mojave:*
   
   High Sierra:*
   El Capitan:
   
4. Press Return after typing the command.
5. When prompted, type your administrator password and press Return again. Terminal doesn't show any characters as you type your password.
6. When prompted, type Y to confirm that you want to erase the volume, then press Return. Terminal shows the progress as the bootable installer is created.
7. When Terminal says that it's done, the volume will have the same name as the installer you downloaded, such as Install macOS Catalina. You can now quit Terminal and eject the volume.

* If your Mac is using macOS Sierra or earlier, include the --applicationpath argument, similar to the way this argument is used in the command for El Capitan.

Use the bootable installer

After creating the bootable installer, follow these steps to use it:

1. Plug the bootable installer into a compatible Mac.
2. Use Startup Manager or Startup Disk preferences to select the bootable installer as the startup disk, then start up from it. Your Mac will start up to macOS Recovery.
   Learn about selecting a startup disk, including what to do if your Mac doesn't start up from it.
3. Choose your language, if prompted.
4. A bootable installer doesn't download macOS from the Internet, but it does require the Internet to get information specific to your Mac model, such as firmware updates. If you need to connect to a Wi-Fi network, use the Wi-Fi menu in the menu bar.
5. Select Install macOS (or Install OS X) from the Utilities window, then click Continue and follow the onscreen instructions.

Learn more

For more information about the createinstallmedia command and the arguments that you can use with it, make sure that the macOS installer is in your Applications folder, then enter this path in Terminal:

Catalina:

Mojave:

High Sierra:

Macos Mojave For Hackintosh

El Capitan: