Personal knowledge management (PKM) is the practice of capturing, organizing and reusing what you learn, so ideas and information are there when you need them. A PKM system has four parts: capture, organize, distill and retrieve. With AI, retrieval becomes asking questions of your own notes, so notes need to be short, sourced and in plain text.
Free: the Second Brain Starter Kit
Seven plain markdown files to set one up this week, in Obsidian or any editor, with Claude or any AI.
What is personal knowledge management?
Personal knowledge management is how one person collects, organizes and reuses what they know: notes, articles, meeting takeaways, ideas and decisions. The goal is not storage. It is getting the right piece back at the moment you need it, so you stop relearning things and start building on them.
The term comes from management research in the late 1990s, as a personal counterpart to company knowledge management. It spread through note-taking communities in the 2010s, where it is usually shortened to PKM.
PKM covers the habits, not a specific app. Someone with a paper notebook and a weekly review practices PKM; someone with a thousand unread saved articles in a fancy tool does not.
What is the difference between PKM and a second brain?
PKM is the practice; a second brain is the system you build to carry it out. Tiago Forte popularized "second brain" as a name for a PKM system kept in digital notes. In everyday use the terms overlap, but PKM describes the discipline and second brain describes the result you can open and search.
Other terms sit nearby. A personal knowledge base is the collection of notes itself. A team knowledge base is the shared version, owned by a company rather than one person; we compare the two in knowledge base vs second brain. For the second brain idea in full, start with what is a second brain.
What are the parts of a PKM system?
Every PKM system does four jobs. Capture: get ideas and sources out of your head and into one inbox. Organize: put each note where you will look for it. Distill: shorten notes to the part worth keeping. Retrieve: find and reuse notes when a task calls for them. Weak systems usually fail at retrieve.
| Step | What it means | Common methods |
|---|---|---|
| Capture | One inbox for everything worth keeping | Quick notes, read-later, voice memos |
| Organize | Put notes where you will look for them | PARA, Zettelkasten |
| Distill | Keep the part that matters | Progressive summarization |
| Retrieve | Get notes back when work needs them | Search, links, and now AI questions |
These map closely to the CODE steps in Forte's book, covered in our Building a Second Brain summary.