Second Brain

Definition
A Second Brain is a digital system that stores information, ideas, notes, and references outside your biological memory. Its purpose is to reduce cognitive load and make knowledge reusable, so your mind stays free for focus, creativity, and decision-making.

A Second Brain is not a specific app or methodology. It is a functional layer that complements your natural memory by providing reliable long-term storage, clear structure, and fast retrieval. People build Second Brains to organise what they learn, support ongoing projects, and avoid losing valuable insights in the noise of everyday work.

In practice, a Second Brain helps you remember what matters, connect ideas more easily, and access information at the moment you need it instead of when you first captured it.

Further reading:
For a full introduction, including origins, benefits, use cases, and the CODE framework, see the complete guide:
→ What is a Second Brain?