A few decades ago, the only well-known way to deliver something to a server, to make it accessible over the internet, was moving files via FTP in Total Commander, FileZilla or FAR Manager, manually copying files and folders from the left pane to the right one. The more advanced among us preferred standard UNIX tools like scp or rsync instead, but the process was essentially the same.
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The quiet revolution happened in 2000. Not on Windows Server, and not yet on Linux — but on FreeBSD, a UNIX-based operating system that was the default choice for IT professionals long before Linux dominated the space.
FreeBSD is worth a brief aside here, because it differs from Linux in a fundamental way. Linux is a kernel. What most people call "Linux" is actually that kernel combined with a GNU userland, a package ecosystem, and a set of choices that vary from distro to distro — Ubuntu, Fedora, and Arch are all running the same kernel but are meaningfully different systems underneath.
FreeBSD ships as a complete, coherent OS — kernel, userland, base tools, and libraries all developed together, versioned together, and tested together as a single unit. That coherence matters. It's part of why FreeBSD solutions tend to be cleaner and why the base system behaves consistently across installations.
The solution FreeBSD built on top of that coherent foundation was called jails. Announced by Poul-Henning Kamp and Robert Watson and shipped as a native kernel feature in FreeBSD 4.0 in March 2000, jails took the chroot idea and completed it — adding full network isolation, process isolation, and proper security boundaries.
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