Tiago Forte's book (pp. 2-4) "Building a Second Brain" mentions the Zettelkasten note-taking approach (p. 4, fn.) as one type of "Second Brain" or "PKM" , i.e. "personal knowledge management".
The book "How to Take Smart Notes" mentioned in the resources below provides a detailed discussion of the rationales for using the Zettelkasten note-taking system and ideas about how to implement it. Page references below are to this book. Below are only some highlights of the Zettelkasten appproach.
The Zettelkasten (slip-box) note-taking system:
The system deploys a typology of various kinds of notes:
Some additional ones:
Implementing Zettelkasten requires considerable diligence. You must be prepared to do extensive work in synthesizing your reading, ideally in your own words -- though see the section about AI summarization tools in this guide.
This system is suitable for people who want to do lots of writing over a significant period of time, want to maintain a large and growing stock of notes they can draw on for various projects, and are committed to developing the habit of actively engaging texts by paraphrasing them within notes. (AI summarization tools may help in this text, if you have time constraints that make it difficult to write your own notes.)
You may find however that your cognitive style or approach to research does not accommodate the Zettelkasten approach (see e.g. 46-49 for a summary of the approach) or that you find some aspects of it useful but not others. Also, you may find that the software used to implement the system (see Roadmap) may not suit your purposes. The point is to develop a system that works for you.
Instead of implementing a note-taking system electronically, you can also use the "analog" format of paper notes.
RESOURCES
Book
The book "How to Take Smart Notes" discusses this system. You can ask for it at the circulation desk in the lobby of Fairchild-Martindale Library, where it is on reserve.
Other resources
Youtubes
See Youtube for many videos about the Zettelkasten note-taking system, including how to implement it in relation to Obsidian and Zotero.