Obsidian
Obsidian is a personal knowledge base and note-taking software application that operates on Markdown files. It allows users to make internal links for notes and then to visualize the connections as a graph. It is designed to help users organize and structure their thoughts and knowledge in a flexible, non-linear way.1
Vault
A vault is a folder on your local file system where Obsidian stores your notes. You can keep all your notes in one vault, or create several vaults for each of your different projects.
Dataview
https://blacksmithgu.github.io/obsidian-dataview/