What is Notion?
Notion is a workflow, knowledge management, and collaboration software platform. It unifies tasks, wikis, and databases with unprecedented customization. Part of the "No-Code Software" movement, it essentially allows users to custom design their own high-performance online software application.
The company describes the app as an all-in-one workspace for note-taking, project management, and task management.
Its greatest strength is its greatest weakness: the massively customizeable blank canvas requires you to decide what you want, and how you want it to work. Unlike other productivity, task management, and knowledge management systems that guide you to their way of doing things, there's no workflow design inherent to notion. It's a set of building blocks for you to shape.
Strong "systems thinking" is necessary to make it work effectively. How you design the system is as important as how you build the element blocks.