Zettelkasten

What It Means

A Zettelkasten, German for "slip box" or "note box", is a note-keeping system in which each idea is written on its own short note, given a fixed number, and linked to other notes it relates to. The best-known one belonged to German sociologist Niklas Luhmann, who filled a box of about 90,000 handwritten notes and described it as a thinking tool. Today the word also covers digital versions of the same idea, built from small linked notes.

How People Say It

• "I keep a Zettelkasten for everything I read."
• "Link it to the note on habits."
• "One idea per note, that's the rule."

The Breakdown

How people apply it today (Buhata's own summary)

1. Write one idea per note, short and in your own words.
2. Give every note a fixed ID so it can be found and linked. Luhmann's own notes carry numbers such as 62,1d13 and 533/4f, mixing digits, punctuation and letters.
3. When you add a note, link it to the notes it relates to, and add a link back from them.
4. Keep a short index of topics, each pointing to a few starting notes.
5. When you write or plan something, start from a note and follow its links.

Short version to try today. Write three separate notes on one thing you read this week, one idea each, and link them to each other.

Luhmann's box by the numbers, per Bielefeld University's archive

Where It Comes From

Zettelkasten simply means "note box" in German. The system is tied to Niklas Luhmann, who researched and taught at Bielefeld University from 1968 to 1993. His box is held by the university's Niklas Luhmann Archive, which has put the notes online as images and searchable transcriptions.

Good to Know

Luhmann's box grew over 45 years, from 1951 to 1996, one handwritten note at a time. Buhata's own suggestion is to add a few notes regularly rather than trying to build the whole thing at once. The Luhmann Archive's digitized box is open to browse online, which shows how his numbering and links work in practice.

Related Terms and Categories

• Second brain

  Tiago Forte's name for a digital store of the notes and ideas you save, organized so you can find them and reuse them in your own work.

• Commonplace book

  A personal notebook of passages, quotations and ideas copied from what you read, filed under topic headings so you can find and reuse them.

• PARA method

  Tiago Forte's system for organizing notes and files into four folders: Projects, Areas, Resources and Archives.

• Note-taking methods

  The common ways to lay out notes from a class, meeting or reading, such as the Cornell, outline, mapping, charting and sentence methods.

• Mind map

  A diagram with one topic in the center and branches radiating out to related ideas, each labeled with a keyword, used to plan, brainstorm or study.

Productivity methods and focus