Zettelkasten (German for “slip box”) is a note-taking method popular amongst some LWers, and often praised for its scalability.

A clear explanation of how this works can be found at abramdemski’s post: https://​​www.lesswrong.com/​​posts/​​NfdHG6oHBJ8Qxc26s/​​the-zettelkasten-method-1