Apple - Does Time Machine restore whole system?

Time Machine by default backs up nearly everything in your macOS partition. It excludes log files, Spotlight indexes, caches, temporary files and trash (have a look: On OS X, what files are excluded by rule from a Time Machine backup?). The backup includes docker files, npm packages, your personal files etc. When the backup is completed, the hard drive will NOT be bootable, meaning that you can't run macOS from your Time machine backup.

You can restore from a Time machine backup without or after installing an operating system. If you restore without installing an operating system:

• All the backup will be restored to your disk, including the operating system (for example Yosemite). [NOTE: If the Mac you are restoring to does not support the version of macOS in your TM Backup, it will still not be able to boot from the restore].
• It can be done from either Recovery or Installation USB. No internet access is required.
• After the backup is restored, everything will be exactly how it was while you were doing the backup.

If you restore after installing an operating system:

• Only personal files and the files you select can be restored and will not restore the operating system.
• Might not restore packages, system tweaks and files that are stored in directories other than traditional ones (for example "/MyApp/mysourcecode.cs" will not be restored by default).

If you think this contains misinformation, please comment because I never actually restored after an operating system installation.

No, time machine has several sorts of exclusions so it does not even back up everything, let alone restore everything. The good news, everything that gets backed up will restore to the same or newer OS.

• On OS X, what files are excluded by rule from a Time Machine backup?

You could review those and be safe knowing you’re set.

Or you could review each time you place things and verify you can restore them (or inspect they are not excluded).

 tmutil isexcluded /path/to/file

I would say you should probably have a clone backup to save your bacon and start with SuperDuper and Carbon Copy Cloner and not mess with disk utility (which can clone a drive) unless you really can’t make one of the purpose built tools to work for your budget and needs. Doing one bootable backup a month and any time you make major changes means you have two different backups and don’t need to update your clone every night (unless you really like that sort of thing).

Read up on either web site for the many potential benefits of a bootable backup, not the least being all files get copied.

• https://shirt-pocket.com/SuperDuper/SuperDuperDescription.html
• https://bombich.com/

In geneal, yes, everything that is important to most users is included in a Time Machine backup. As stated in other answers, there are a number of restrictions regarding OS bootability and excluded system files and the likes, and there are certain computer-bound features like software activation of for example Adobe software that doesn’t transfer with a backup.

In most cases, you can simply buy a replacement Mac, connect the drive, and restore al the files you like, or the complete system from a Time Machine backup. Time Machine is well-documented in macOS help and on Apple’s website for more in-depth (and ever changing) information.