org-mode is a loose-specification for an outline markup and a fairly powerful API for building simple applications on top of that outline markup. In searching for Nirvana, many have implemented syntax highlighting and outlining functionality for other text editors and programming environments like: vim-orgmode sublime-text plugin vscode-org-mode python orgparse, etc. These provide basic support for the first part of org-mode and discount the second entirely.
Consider org-drill
or org-fc, two
examples of an Anki deck for org-mode. Given an org-mode document with
certain shape-properties, spaced-repitition learning can be done; the
document can be shared and exported to the web or to a PDF. org-drill can use the facilities provided by
org-mode to filter and select which cards to test, and can store
metadata alongside the objects themselves.
The org-agenda is another example of this, built in to org-mode
itself. org-agenda can look over all the
headings in a set of org-mode files and present ones which need to be
worked on, again filtered and selected with a comprehensive set of
tools.
Critically, all these things work together. When I have reviews in org-drill that are overdue, they can appear on my org-agenda.
org-roam and the CCE are also org-mode meta-applications. My Practice Captures may be, I am unsure.
This is an implementation of Hypermedia.