|Revert To keeps multiple versions of your iWork files|
with a UI similar to Time Machine.
Steve Jobs first demonstrated Time Machine about a dozen years ago. It's a simple backup feature built into macOS that takes hourly backup snapshots of files on your computer, when they change. This makes its trivial to recover a file your deleted or overwrote. The biggest challenge is enabling it with an external hard drive (which isn't much of a challenge at all).
Even BetterBut, what if you didn't setup Time Machine? No worries, since backing up work is such a valuable feature Apple has incorporated versioning into their iWork suite of applications for word processing (Pages), presentations (Keynote), and spreadsheets (Numbers). At any given time, you can step back to earlier document versions in iWork; no setup required (screen shot, above).
I wish other major software suites, like those from Adobe or Microsoft, would implement this simple feature.
To step back to an earlier version of your iWork file, simply go to File –> Revert To and, voilà, your previous versions are there. This out-of-the-box feature, coupled with Time Machine, will solve nearly all of your common backup needs. I say nearly because all of your backups will still be local to your computer and network. For the most mission critical redundancy, I recommend a 3-2-1 backup policy: Three backups on at least two different media, with one backup located offsite (i.e. Amazon S3 or Glacier).