For me, it was a wiki/knowledge base - I’ve had dozens over the years as I’ve tried to find the ‘right’ one, but I’m currently a fan of @bookstack@fosstodon.org. My brain’s not always the most reliable, and so my wiki becomes my ‘external brain’. A lot of people are using things like Obsidian/Notion/etc in the same way.
For me, it was a wiki/knowledge base - I’ve had dozens over the years as I’ve tried to find the ‘right’ one, but I’m currently a fan of @bookstack@fosstodon.org. My brain’s not always the most reliable, and so my wiki becomes my ‘external brain’. A lot of people are using things like Obsidian/Notion/etc in the same way.