The Zettelkasten method: a slip box of linked notes for thinking and writing

The Zettelkasten method is a way of thinking and writing with a box of small notes. Each note holds one idea, written in your own words. Each has its own address, and each links to the notes it relates to, with a sentence saying why. Over the years, the links grow into a web of ideas you can walk through, and new thoughts come from the connections.

This guide covers where the method comes from, its parts, the mistakes that turn it into a dumping ground, and how to keep a Zettelkasten in Barside, a free desktop app for Windows, Linux and Mac.

Where the Zettelkasten method comes from

Zettelkasten is German for slip box: a box of paper slips. No one person invented it as a brand. The best-known user, and the reason the method is famous, is the German sociologist Niklas Luhmann (1927-1998), who taught at Bielefeld University from 1968 to 1993.

Bielefeld University, which acquired his estate in 2011, describes his Zettelkasten as about 90,000 notes written between 1951 and 1996. Zettelkasten.de, the site of Sascha Fast and Christian Tietze, notes that Luhmann published 50 books and over 600 articles, and that he gave credit for this to "working in a partnership with his Zettelkasten".

Zettelkasten.de defines the tool this way: "A Zettelkasten is a personal tool for thinking and writing. It has hypertextual features to make a web of thoughts possible." On paper, a link was another slip's number written on the slip. In an app, it is a click.

The parts of a Zettelkasten

Zettelkasten.de describes a handful of principles. Together, they make the box useful for thinking rather than just for storage.

One idea per note

This is called atomicity. A note holds a single idea, small enough that you can link to exactly that idea from anywhere. A note called Spaced practice beats cramming is atomic. A note called Learning is not.

A fixed address

Every note has a unique identifier, so other notes can point to it. Luhmann used a numbering scheme of his own. Others use a timestamp, and any unique string works. What matters is that the address never changes, so links never break.

Links, with the reason

Links connect a note to related notes, and you write why they are connected. Zettelkasten.de puts it in one line: "Emphasize connection, not a collection." A link that says "this contradicts" or "this is an example of" is worth far more than a bare list of related titles.

Structure notes

Some notes exist to organize others: a table of contents for a topic, a hub, an outline for an essay. They give you entry points into the web, so you do not have to remember where everything is.

Your own words

The body of a note is written by you, not copied. Rewriting an idea is how you check that you understood it, and it makes the note fit with the rest of your thinking.

References

Each note cites where the idea came from: a book and page, an article, a conversation. For an idea of your own, the reference stays empty.

Common Zettelkasten mistakes

• Copying instead of rephrasing. Pasting a quote into a note feels productive, but it skips the thinking. Keep quotes in a source note and write the idea in your own words in the Zettelkasten.
• Links without a reason. A note that ends with five related links and no explanation is hard to use later. Say in a sentence why each link is there.
• The collection mindset. Treating the box as storage, where the goal is more notes, is the trap zettelkasten.de warns about. The goal is connections and writing.
• Notes that hold too much. A note with three ideas cannot be linked precisely. Split it.
• Waiting for the perfect setup. The method is old and simple. Start with one idea and one link today.

How to keep a Zettelkasten in Barside

Barside's notes were built around links. Type [[ in any note to link another note, and every note shows a Linked from list with the sentence around each link. Here is a setup that follows the principles above.

Set up the box

1. Create a workspace called Zettelkasten (or Slip box) with + next to Workspaces in the sidebar. A separate workspace keeps your idea notes apart from meeting notes and to-dos, while links still cross workspaces when you need them.
2. Keep a second workspace, Sources, for notes about books, articles and talks. Point Settings → Reading → Save new items in at it, so saved articles land there too.

Write one idea per note

1. Press Ctrl+N in Barside, or press Alt+Shift+Space in any app and type nn followed by the idea.
2. Title the note with the idea as a short statement, like Small notes are easier to link than long ones.
3. Write a few sentences in your own words. Add a line at the bottom with the reference, like Source: followed by a link to the source note.

Give every note a fixed address

In Barside, a link points to the note itself, not to its title. Rename a note and every link to it shows the new title, so the address never breaks. If you like seeing an ID, start each title with a timestamp such as 202610021430. The search bar finds a note by any part of its title.

Link with a reason

1. While writing, type [[ and a few letters of a related idea. Choose it with the arrow keys and press Enter.
2. Write the reason in the same sentence, such as "This contradicts [[Cramming works for exams", and pick the note.
3. If the idea you want to link does not exist yet, choose Create note at the end of the list. Barside makes the new note and links it in one step, and you fill it in later.

The Linked from list under the other note shows that whole sentence, so the reason travels with the backlink. See linked notes and backlinks for how links behave.

Build structure notes

When a topic has a dozen notes, write a structure note for it: a short introduction and an ordered list of links, each with a line of context. Open Note options and choose Pin to the top, so your structure notes lead the workspace. The guide to maps of content goes deeper on hub notes.

Walk the web on the note map

Open Note map in the sidebar to see every linked note as a dot and every link as a line. Bigger dots have more links, so your hubs stand out. Choose Show all notes to find loose notes with no links, then link them or delete them. Filter the map to the Zettelkasten workspace to see just your idea notes. See the note graph view.

Bring an existing slip box

If you kept a Zettelkasten in Obsidian, Settings & backups → Import notes reads the vault folder and turns its [[wikilinks]] into Barside note links, so your web arrives intact. See how to import your notes.

Limits worth knowing

• Links point to whole notes. There are no links to a heading or a block inside a note, which suits atomic notes anyway.
• Linked from lists real links only. Plain mentions of a title are not listed; search for the title to find them.
• The assistant can connect related notes with links if you connect an AI, but a link made for you carries no reason. Write the why yourself.

Who the Zettelkasten method suits

• Writers and academics who produce long texts from many sources.
• Students working toward a thesis, who need their reading to add up to an argument.
• Researchers and analysts who want ideas to meet across projects.
• Lifelong learners who want their notes to talk to each other.

It suits people less if they mainly need to file documents or track tasks. A Zettelkasten is slow to pay off, and it rewards regular writing. For filing by project, the PARA method is quicker to start.

Related methods

• Maps of content, Nick Milo's hub notes for gathering and navigating ideas.
• Progressive Summarization, layers of bold, highlight and summary on your source notes.
• Building a Second Brain, Tiago Forte's project-centered way to save and use what you learn.
• Cornell note taking, a lecture method with cues, notes and a summary.