Everything is a package

I mean, pretty much. Or rather, everything is in a package. Back in the old days they were called source distributions or .tar.gzs and you compiled everything yourself. Gentoo, for example, still does everything that way, but uses the name 'package' anyway.

The coreutils package, or something like it, contains multiple commands that a bare bones, command-line-only system would need, but some things are built into the shells. e.g. cd is always shell-based. echo may or may not be. ls (dir) is in coreutils.

There are also things like busybox that, in a single executable from a single package, contains a stripped-down version of everything in coreutils, a shell and a handful of other things too.