Start

There are two types of macOS installers:

• Online, this method uses the basic recovery macOS environment called recoveryOS. It downloads the OS files from Apple's servers at install time, which requires a stable internet connection. This method can be done on basically any OS.
• Offline, this method downloads the full macOS installer, which requires no internet connection at install time. This method is available only on macOS. Windows users might be able to follow this reddit post