Install & Recovery covers the tools and procedures used when you need to reinstall macOS, create installation media, enter macOS Recovery, repair a startup disk, or troubleshoot a Mac that cannot start normally.
macOS Recovery
macOS Recovery provides tools for reinstalling macOS, checking disks, restoring from backups, and performing other recovery tasks. The startup procedure differs between Apple silicon and Intel-based Macs.
Reinstall macOS
A normal reinstall from macOS Recovery is designed to replace system files without intentionally erasing personal files. Even so, important data should be backed up before reinstalling whenever possible.
Bootable macOS Installers
A bootable installer can be useful for offline installation, troubleshooting, or installing the same compatible macOS release on multiple Macs. Creating one requires the full macOS installer and a suitable external drive.
Startup Disk Problems
If a startup disk is missing or cannot be repaired, avoid erasing it until you have considered whether important data needs to be recovered. Disk failure and file-system damage can require a different approach from ordinary macOS corruption.
Data safety: Erasing a disk is fundamentally different from reinstalling macOS over an existing system. Read each step carefully and verify your backup before choosing an erase operation.