With Mac OS X Lion and a new piece of free software, it’s easier than ever to create a USB keychain that you can boot from.

How-To How to create a bootable USB macOS installer Make a macOS installer with createinstallmedia and install Sequoia, the latest beta, or any macOS on multiple Macs, or do a clean install.

The OS X 10.10 Yosemite installer from the Mac App Store in your Applications folder. The installer will delete itself when you install the operating system, but it can be re-downloaded if necessary.

Though you can install Mavericks (OS X 10.9) directly from your Mac's hard drive, a bootable installer drive can be more convenient for installing the OS onto multiple Macs. And if your Mac is ...

How to create a macOS Monterey USB Install drive for quick and easy installations of Apple's latest operating system for Mac.