Microsoft technical documentation used to be called MSDN and there was a time when we used to install it on development machine along with Visual Studio. A lot has changed over the past decade.
Now the technical documentation is called Microsoft Docs. It has improved a lot recently. I love the dark theme and improved search and navigation. Gamification of the tutorials and badges have also enhanced the overall experience. But the killer feature is Azure Sandbox available to try out stuff right inside the browser.
What makes it even better is the full-fleshed VSCode based IDE built into the docs.
For simpler .Net exercises which don’t require a whole lot of infrastructure, there is .NET Editor available in the browser. It is based on WebAssembly which makes it much faster than earlier solutions.