Building a Second Brain: the CODE method, step by step

Building a second brain means keeping what you learn in one trusted digital place, outside your head, so you can find it and use it when it counts. The best-known version of the idea is Building a Second Brain by Tiago Forte of Forte Labs. It rests on four steps called CODE: Capture, Organize, Distill and Express.

This guide explains each step, the mistakes Forte warns about, and how to run the whole method in Barside, a free desktop app for Windows, Linux and Mac that keeps your library on your own computer.

What Building a Second Brain is

Tiago Forte describes a second brain as "an external, centralized, digital repository for the things you learn". He also calls it "a methodology for saving and systematically reminding us of the ideas, inspirations, insights, and connections we've gained through our experience."

The problem it solves is familiar. You read articles, sit in meetings, listen to podcasts and have ideas on a walk. A week later most of it is gone. A second brain catches the useful part and keeps it where your future self can use it: in a project, a piece of writing or a decision.

Forte teaches the method in an introductory guide on the Forte Labs blog and in his book Building a Second Brain, published by Simon & Schuster on June 14, 2022. The official site sums it up as a "4-step process for consistently turning the information you consume into creative output and concrete results."

Two of Forte's other methods slot into it. The PARA method handles the Organize step, and Progressive Summarization handles Distill. Each works on its own, but they were made to fit together.

The four steps of CODE

Capture: keep what resonates

Capture means saving the ideas and insights you think are worth keeping, not everything you read. A quote that surprised you, a chart you want to reuse, the one sentence from a call that changed your mind. Your own judgment is the filter. If nothing in an article struck you, there is nothing to save.

Organize: file by action, not by topic

Organize means filing what you saved by how actionable it is: by the projects and goals it helps, rather than by subject. Forte uses PARA for this, with four groups: Projects, Areas, Resources and Archives. A note about pricing goes into the project where you will use it next, not into a broad folder called Marketing.

Distill: find the essence

Distill means boiling a note down to its essence, so it is quick to use later. Progressive Summarization does it in layers. You bold the key passages, highlight the best of those, and write a short summary in your own words at the top. You add a layer only when you are already using the note, not all at once.

Express: make something with it

Express means turning notes into real output: sharing, publishing, making something. A second brain that only collects is a storage room. The point is the presentation, the essay, the plan or the decision your notes made easier. Expressing also shows you what to capture next, because you see which notes you reached for.

Common mistakes when building a second brain

Forte's guide names a handful of traps. They are worth reading before you set anything up.

• Designing the perfect folder structure first. A beautiful hierarchy with no notes in it helps nobody. Start with a few broad groups and let the structure grow from real projects.
• Sorting all your old notes at once. Moving years of notes into a new system is a project that rarely ends. Start fresh, leave the old pile where it is, and pull from it only when a project needs something.
• Consuming passively. Saving is not learning. If you never come back to what you captured, the library grows and your work does not change.
• Waiting until work is finished before sharing it. Express early. A rough draft shared with a colleague teaches you more than a perfect one kept in a drawer.

A fifth trap follows from the first step: capturing everything. When you save whole articles without a reason, you rebuild the noise you were trying to escape. Keep the passage, not the page, unless you truly need the page.

How to build a second brain in Barside

Barside is a desktop app that holds notes, reading, tasks, bookmarks, recordings and drawings in one library on your computer, with no account needed. Here is how each step of CODE maps onto it.

Capture in Barside

• Articles and newsletters. Save a page to Reading: paste a link, choose Save the page open in your browser, or press Alt+Shift+Space in any app and choose Save to Reading. Newsletters can arrive by email at your own Barside address. Select a passage to highlight it, with a comment if you like, and the Highlights list keeps them all. See the read-it-later inbox with highlights.
• Ideas. Press Alt+Shift+Space in any app, type nn and a title, and press Enter. Barside makes the note in your first workspace without pulling you out of what you were doing.
• Text on your screen. Press Alt+Shift+S, drag across anything, and Barside reads the text on your computer and can add the capture to a note.
• Pages as they look. Save a webpage into this note, the download icon in the note toolbar, keeps an offline copy of a page inside a note.
• Calls and voice. Record audio into a note, or transcribe a call on your computer, so the sentence that mattered is searchable later.

Organize in Barside

Workspaces do the job of PARA's top-level folders. Create four of them, named Projects, Areas, Resources and Archives, each in its own color. Then open Settings → Reading and set Save new items in to Resources, so saved articles land there. The PARA method guide walks through the setup in detail, including what to do when a project ends.

Inside a workspace, link notes by typing [[. A note can live in one workspace and still be linked from every project that uses it, so you never need two copies. See linked notes and backlinks.

Distill in Barside

The note toolbar has bold and a highlight color, so Progressive Summarization works the way Forte describes it: bold the key sentences, highlight the best of the bold ones, and add a few lines of summary at the top. Do it when you open a note for a project, not on the day you save it.

For an article in Reading, choose Keep as a note when it becomes part of your work. It moves into your notes, where you can format it, write around it and link it.

Express in Barside

• Draft where your notes are. Write the essay, plan or talk in a note, and link the sources you used with [[, so Linked from under each source shows where it ended up.
• Ask your library first. Ask library, in Library & briefing, finds the passages in your notes and Reading that match a question and has the AI you connect answer from them, with each source cited. Barside has no AI of its own; you connect Claude, ChatGPT, Gemini or OpenRouter in Settings → AI. See AI search over your notes.
• Share for feedback. Share note to a Space posts a copy of a note to a private Space, where people can read and discuss it.
• Turn next steps into tasks. Write them as a checklist. Every checklist item shows up on the task board.

Your first week, step by step

1. Create the four PARA workspaces and give each a color.
2. Pick one project you are working on now. In Projects, choose From template, pick Project brief, and fill in the goal. Open Note options and choose Pin to the top so it leads the workspace.
3. For a week, capture only what touches that project or something you care about: highlights in Reading, quick notes with nn, screen text with Alt+Shift+S.
4. On Friday, open each new note once. Move it to the right workspace with the selector above it, and link it to the project brief with [[.
5. Distill the two or three notes you used most: bold, highlight, summary.
6. Express one small thing from them: a message, a one-page plan, a short post.

Repeat the cycle. A Weekly review template, set as a repeating note every Friday, keeps the rhythm going without you having to remember it.

Who Building a Second Brain suits

The method fits anyone whose work depends on what they have read, heard or thought before:

• Writers, researchers and students, who collect sources and need to find the right passage months later.
• Consultants and freelancers, who carry knowledge from one client project to the next.
• Managers and team leads, whose decisions rest on meetings, documents and conversations.
• Creators, who turn notes into posts, videos and talks.

It suits people less if they rarely reuse information, or if they want a fixed system they never adjust. And since Barside is a desktop app with no phone version, it fits best when you do your capturing and thinking at a computer. If most of your ideas arrive on a phone, compare the options in the best second brain apps.

Related methods

Building a Second Brain borrows from, and pairs well with, other ways of working:

• The PARA method, Forte's four groups for organizing by actionability.
• Progressive Summarization, Forte's layer-by-layer way to distill notes.
• The Zettelkasten method, small linked notes in your own words, for thinking and writing.
• Maps of content, hub notes that gather and arrange ideas on one topic.
• Getting Things Done, David Allen's system for the actions your projects need.