Is Time Machine archival? If I removed it from my external drive, would be files be removed from my external drive?

Time Machine is an application that runs on your Mac, you cannot put it on an external drive.

You made backups to the drive using Time Machine. If you remove the external drive, the backups will remain in whatever state each was in at the time. Your files would remain on the drive, but if you delete any from your computer, they would eventually "fall out" of the backup depending on how much space you have on the drive. Learn more: https://support.apple.com/en-us/HT201250

If you want true archival storage of everything for posterity, you could simply move those files independently or burn each to an m-disc compatible CD or DVD.

Please read the directions for Time Machine in Back up your Mac with Time Machine and let it run as Apple intended it to. Do NOT disconnect it unless there is a problem with the Time Machine backup External Hard Disk. Please do not overthink Time Machine it is simple and it works fine when left alone, when users try to out think Apple engineers that is when they begin having issues.

annepeterson1 wrote:

I am new to Time Machine, is it archival?

Time Machine maintains copies of files found on the source Mac, and maintains copies of the changes made to those files over time, up to the capacity of the storage device. This includes maintaining copies of deleted files. Once the capacity of the storage device is reached, then the oldest files will be deleted from the backup to make room for the newest changes.

This isn’t what some will call “archival” storage.

If you need permanent copies of your data, you will want to review other options, and consider (for instance) the longevity of recorded optical media such as CD or DVD, or that of magnetic tape, or whatever you might choose to use as your archival storage, as well as the availability of devices to read those archives.

Will my files stay backed up on this external drive if I delete them from my computer?

Time Machine will maintain copies of those files until storage capacity is reached, when the storage used for the oldest files will be reclaimed. If the Time Machine backup is disconnected or de-configured, then there will be no changes made (by Time Machine) to the Time Machine backup.

Time Machine can maintain multiple backups in parallel. Some folks have used this for a backup or two at home, and a backup or two kept at the office or school or shop, for instance.

A large-capacity storage device (a big hard disk, a NAS RAID array, etc) can potentially go a year or more before needing reclamation, depending on how much you churn your source storage.

I’d tend to run multiple backups in parallel, lest one of the backups fail or become corrupted.

If you need to go back to a backup of a file from a specific day for an arbitrary date in the past, Time Machine isn’t your tool. If you need copies of files active and not deleted from however-big-your-backup-device-is, then Time Machine works well.

If you’re using a portable Mac, then network-attached storage with Time Machine support can mean you get backups whenever you’re connected to the same Wi-Fi with the network-attached storage. Network-attached storage with Time Machine support can also be shared across multiple wired- or Wi-Fi-connected Macs.