How to Set Up Time Machine Backups on macOS
Time Machine is macOS's built-in backup solution. It automatically backs up your entire Mac to an external drive or a network location.
Connect a Backup Drive
Connect an external drive with enough space (at least the same size as your Mac's storage).
Configure Time Machine
Go to System Settings > General > Time Machine, click Add Backup Disk, and select your drive.
Manual Backup
tmutil startbackup
Exclude Folders
tmutil addexclusion ~/Downloads