Zettelkasten

https://en.wikipedia.org/wiki/Zettelkasten

A Zettelkasten (German: ‘slipbox’, plural Zettelkästen) or card file consists of small items of information stored on Zetteln (German: ‘slips’; singular: Zettel), paper slips or cards, that may be linked to each other through subject headings or other metadata such as numbers and tags. It has often been used as a system of note-taking and personal knowledge management for research, study, and writing.

Note-taking with Zettelkasten - An Introduction ↓

https://www.youtube.com/watch?v=o1NJYnZCfmY

11:43 writing in your own words you ensure that you truly understand it before you put it into your notetaking system so when you find yourself unable to rephrase an idea or to to write it down in your own words it’s it’s a very clear indication that you haven’t fully grasped it yet …

Cli zettelkasten golang app ↓

https://github.com/zk-org/zk Looks very powerfull (untested).
https://www.youtube.com/watch?v=Ck4TriLMR4s

Author notes that organization/linking of notes should be done by depth, where more general concepts are at the top of the pyramid, and more specific at the bottom.

nb, another cli note taking script written in bash ↓

https://xwmx.github.io/nb (untested)

nb is a command line and local web note‑taking, bookmarking, archiving, and knowledge base application