The second brain is Tiago Forte's term for an external system that captures, organises, and resurfaces ideas you encounter, so your biological brain doesn't have to.
Why it matters
Forte's 2022 book *Building a Second Brain* popularised the CODE method (Capture, Organise, Distill, Express). The framework's value is its emphasis on **distillation**: a raw bookmark is low-value, a highlighted passage is medium-value, a summary connecting that passage to others is high-value. The job of a second-brain tool is to make distillation cheap.
Most second-brain implementations sit in note-taking apps (Notion, Roam, Obsidian, Mem). They share a manual-authoring assumption: you write the summary. AI-augmented variants (Mem.ai, Pith) reduce the authoring cost in different ways — Mem augments your writing, Pith generates the distillation from sources you've already saved.
How Pith relates
Pith automates the distillation step: bookmarks become topic-clustered, citation-linked wiki pages without your input. The Capture and Organise steps are also reduced (one keystroke, auto-tag). Express remains your job — Pith is the second brain, not the first.
See also
Last reviewed: 10 May 2026 · Licensed CC BY 4.0 · cite freely with attribution to Pith.