How to use Time Machine
Set it and forget it — once done, you won’t even know Time Machine is running
Time Machine backs up your Mac at hourly intervals, copying only those files that have changed since the last backup.
TIME MACHINE CREATES incremental backups of your Mac. This means that every time a backup runs, it copies only the files that have changed since the previous backup. It saves snapshots of your data once every hour for the previous 24 hours, once a day for the past month, and once a week for all previous months. That way, you can roll your Mac back to the state it was in at any point in the previous 24 hours, as well as recover files that were deleted a month ago. Time Machine keeps monthly backups until it runs out of storage space, at which point it deletes the oldest. As well as using Time Machine to recover files, you can use it with macOS Recovery when you reinstall macOS to recover settings from your previous install.