Obsidian Canvas is a new feature that provides an infinite space for users to research, brainstorm, diagram, and lay out their ideas. It allows users to organize notes visually and embed various media types, including images, PDFs, videos, and web pages. The Canvas files are stored locally in a JSON-based file format that is open-sourced and designed to be extensible. This feature is part of the Obsidian knowledge management tool, which aims to provide a personal wiki-like experience.