Short answer. Fleeting notes are the Zettelkasten term for quick scribbles you fully intend to process later. Three rules make them work: (1) capture the moment you think it — zero friction, (2) collect everything in one inbox, (3) process within 24-48 hours, then throw the note away. They do not need to be well written. They need to exist before the thought evaporates.

What fleeting notes are (and where they sit in Zettelkasten)

In How to Take Smart Notes, Sönke Ahrens describes the note-taking system of sociologist Niklas Luhmann — the Zettelkasten — and splits notes into three kinds: fleeting notes, literature notes, and permanent notes. Fleeting notes are not where knowledge lives; they are a temporary net so a passing thought doesn’t get away (the zettelkasten.de introduction is a good primer).

The three note types, side by side

TypeJobLifespanWriting bar
Fleeting notesCatch passing thoughtsUntil processed (1-2 days)A scribble is fine
Literature notesSummarize what you readLong-termYour own words, with source
Permanent notesYour own ideas, crystallizedPermanentOne idea per note, full sentences

How to write one (real examples, no perfectionism)

There is no correct format. The bar is "future me can reconstruct this." Examples:

- Pricing page FAQ: reordering might cut drop-off?
- "Habits are environment design" - walk-home thought, find source
- Weakness of plan A: first-launch explainer too long

Three habits help: add one word of context ("plan A," "pricing page"), use your own phrasing rather than quoting, and keep to one thought per note so sorting stays easy.

The 3 rules that make fleeting notes work

Rule 1: Zero-friction capture

A slow-launching tool kills the thought all by itself. Aim to be writing within about three seconds — a card in your pocket or an app you can reach instantly both qualify.

Rule 2: One inbox only

Scattered inboxes are the number-one reason this practice collapses. If notes end up on paper, in three apps, and in chat messages to yourself, you add a "find it" step before every "process it" step. Decide on the one place everything lands.

Rule 3: Process within 24-48 hours

Ahrens recommends processing within a day or two. Wait longer and "what did I mean by this?" piles up until the inbox is just a junk drawer. Processing means deciding: develop it into a permanent note, convert it to a task, or delete it.

The processing flow: inbox → evaluate → promote or discard

  1. Open your inbox once a day.
  2. For each note ask: "Is this raw material for my own thinking?"
  3. Yes → rewrite it as a permanent note (in Obsidian or wherever your notes live), in your own words, as a complete thought.
  4. It was actually a task or event → move it to your task manager or calendar.
  5. Neither → delete it.

Most fleeting notes should die here — and that is the system working, not failing. Permission to discard is what keeps capture effortless.

Choosing a capture tool: paper, stock notes, or email-based

  • Paper / index cards — fastest pen-to-idea, but everything must be re-typed into your digital notes later
  • Stock notes app — easy, but unprocessed scraps sink between other notes with no pressure to deal with them
  • Email-based capture — every note lands in your inbox, which doubles as a processing queue you cannot ignore

An example of the email-based route is Simple Memo - for Obsidian: it launches in about a second, takes typed or dictated input, and one tap sends the note to your inbox while auto-appending it to an Inbox note in your iCloud Drive vault — feeding the exact Obsidian workflow where permanent notes get written. For the full menu of capture routes, see 6 ways to capture notes in Obsidian from iPhone.

FAQ

Are fleeting notes meant to be deleted?
Yes. Once a note has been processed — turned into a permanent note or judged unneeded — you throw it away. Being disposable is exactly what makes them effortless to write.

How are fleeting notes different from a daily note?
A daily note is a place for the day’s record; a fleeting note is a thought waiting to be processed. They combine well: many people use the daily note as the inbox where fleeting notes collect.

What should I write fleeting notes in?
Anything that lets you start writing within about three seconds and collects everything in one place. Paper, the stock notes app, or an email-based capture app are the usual picks. The one real mistake is scattering them across tools.

What is the difference from literature notes?
Literature notes summarize something you read, in your own words, kept long-term with the source. Fleeting notes are quick scribbles of your own passing thoughts, discarded after processing.

For the full Zettelkasten workflow, see Zettelkasten with email capture; for the capture-first philosophy behind it, see building a second brain.