What is a Zettelkasten?

Because a definition is surprisingly hard to come by!

April 29, 2019Filed under blog#note-taking#writing#zettelkastenMarkdown source

Assumed Audience: People interested in note-taking, effective learning, or the idea of a Zettelkasten (which I’ve written about before).

A friend recently asked me: “What exactly is a Zettelkasten?” Unfortunately, there aren’t any (easy-to-find, anyway) answers in a single place online… hopefully until today!1 The short answer is: a well-organized box (or group of boxes) of notecards. The word itself is just German for an index card box. Given you likely landed here via an internet search, though, I expect you might want a bit more.

A Zettelkasten as an idea dates to the work of the 20th century German sociologist Niklas Luhmann, who used a large system of carefully labeled notecards (an index card is a zettel) as a form of hypertext. (The linked Wikipedia article notwithstanding, hypertext works perfectly well without any digital technologies: the real key to the idea is links that you can easily follow.) In the system Luhmann devised, each notecard gets a unique identifier, which can then be used to reference it from other notecards, and which have a well-defined order of some sort.2 They can also have keywords—tags—that group them into related sets of ideas. A full Zettelkasten also usually includes not just individual notes but also organizational notes. These serve as pointers and structure for whole other sets of notes—summaries of sets of knowledge you’ve built up over time.

Using this strategy transforms a collection of notes into a web of notes. If you build up that web carefully, you can follow the connections between notes in novel directions over time. This is great for memory, because it helps you cement those relationships in your own mind. Even more importantly, though, working with your notes as a network can produce brand new questions and ideas. Connections that were not immediately apparent can become so as you add more links and structures to the system. The Zettelkasten becomes a tool not merely for recollection but for thought.

The beauty of this approach is its simplicity: A Zettelkasten is just a low-overhead, high-value way of creating, managing, and making use of a system of notes. It can use notecards, or any good note-taking app, or any combination of things that lets you easily “link” to and therefore navigate between notes. Its power is not in spite of but precisely because of that simplicity!

Further Reading

If you’d like to dig deeper into this, I recommend the posts I have found most helpful:

  • Communicating with Slip Boxes – Luhmann’s own account of working with his Zettelkasten, and the thing I wish I had read first! I particularly found this thought helpful as I have begun building my own set of notes:

    Usually it is more fruitful to look for formulations of problems that relate heterogeneous things with each other.

  • my Zettelkasten – Alan Jacobs, with the piece that introduced me to the concept at all, and with an interesting twist on the idea that works particularly well for him (it would not, I think, for me… but there is some overlap with his needs and what I’m doing with the aforementioned project!).

  • Create a Zettelkasten for your Notes to Improve Thinking and Writing – from Zettelkasten.de, tracing out similar themes to what I do here. I have found the site to be a pretty good resource in general.


  1. I first learned about the idea from Alan Jacobs, and then more from a dedicated site—but while Jacobs’ post gives a reasonably good summary, as does this post on that dedicated site, neither has much search prominence.

  2. I’ve chosen to organize my own Zettelkasten by date, because I find that seeing what I was thinking at a particular time can be very helpful and very interesting, and it’s also often a helpful way of remembering things.