How Apple adopted a triplet version numbering scheme by 1988, then complicated it with additional revision numbers, Supplemental Updates, RSRs, and more.
package
From Installer packages and metapackages, to the first for Big Sur with its new boot volume group. RSRs and their demise, and when an upgrade is an update.
From the resource forks of Classic apps, to versioned and new-style bundles in 2001, document packages, then the incorporation of signatures and notarization tickets.
From the Mac OS Installer app for 9.1 in 2001, through updates in the App Store, to Software Update settings, with Content Caching servers on the way.
Download some vital free software, mount its disk image, run the Installer package there – but why does Ventura refuse to install it, and what you do?
The Finder is happy to create aliases to most files and folders, provided they aren’t immediately inside a bundle or package. Then it gets all fussy. But why?
How macOS updaters have changed over the last decade, and why they’re far more reliable, but you can’t download a standalone updater any more.
App signatures remain valid forever, but Installer packages are different, and their certificates can and do expire. What about notarization though?
If you use the Installer app the wrong way, it will open an ad-hoc signed package and quietly install apps which don’t get checked by Gatekeeper.
Stepping through building it correctly in Xcode, turning it into an Installer package getting it notarized and the ticket stapled to the tool.
The Eclectic Light Company 