A second brain is essentially your note taking strategy. Its a way of retaining things you may forget and surfacing them back up when you are needing to create or "get productive". It helps to "learn in public" and surface what you know in case it can help others, but also surface questions that perhaps others may have and can answer for you. Alternatively those same questions may exist in others and a collective effort to getting the answer may be the only means of getting things answered.
Typically its NOT done amongst the lazier amongst us, or those shy of what they know or curious about, so if that's you look the other way! đ (no, I'm NOT thinking of 15-16 year olds amongst us and all the Gens between that age and mine)
I cannot replicate what the godfather of this movement has done on his site - so check out https://www.buildingasecondbrain.com/ for all manner of resources and guidance.Â
For my part I have in the year 2023 build a second brain (BASB) primarily using a freemium tool called Workflowy, which I had been using for many years. This was after an initial enchantment with Logseq, a tool I still hope finds its way to becoming a better self hosted solution one day. To learn a bit more about Workflowy and how to use it check out their Youtube playlist
For my Second Brain I have internally structured it into the sections of Projects, Areas, Resources and Archive (PARA)
I have also felt the need to define a structured workflow to get my outputs from my inputs and have based this on Capture > Organise > Distill > Express (CODE). Check out my  second brain deep link on this
Click on the image below to be taken to my Youtube playlist on all of this stuffÂ