Obsidian is a note-taking app, but that description undersells it. The thing that makes it different from Notion, Roam, or any of the cloud-based alternatives is this: your vault is just a folder of Markdown files on your computer. No proprietary database, no sync service you're locked into, no account required. Just .md files sitting on disk, organized however you want. That simplicity is also what makes it uniquely useful as a context layer for AI. What Obsidian Actually Is The core features: a Markdown editor with live preview, a graph view that visualizes how your notes connect via backlinks, and a community plugin ecosystem with over 1,000 plugins. It runs on Mac, Windows, Linux, iOS, and Android. Sync is optional and paid, but your vault works completely offline. What you build in Obsidian is a personal knowledge graph. Each note links to others via [[wikilinks]] . Over time, the graph view shows you which ideas are densely connected and which are isolated. It's the...