A second brain is a system for organizing and managing information to enhance learning, productivity, and personal growth. It is an external, centralized, digital repository for the things you learn and the resources from which they come. Building a second brain is a methodology for saving and systematically reminding us of the ideas, inspirations, insights, and connections we’ve gained through our experience. It provides a clear, actionable path to creating a “Second Brain” that ultimately expands our memory and our intellect using modern tools of technology. By offloading our thinking onto a second brain, we free our biological brain to imagine, create, and simply be present. A second brain helps us eliminate distractions and focus on difficult problems. The precise steps of both creating and using a second brain will depend on your working style, personality, and specific needs. However, there are some general principles everyone should keep in mind for building a second brain successfully, such as choosing a guiding philosophy and selecting the right tools. Building a second brain can lead to many benefits, including less stress, better focus, more insights, and enhanced productivity.