I can\'t quite believe I am asking this question, but I have not been able to find a definition in the documentation. In case it isn\'t painfully obvious, I am (very) ne
They call it a multi-root workspace, and with that you can do debugging easily because:
"With multi-root workspaces, Visual Studio Code searches across all folders for launch.json debug configuration files and displays them with the folder name as a suffix."
Say you have a server and a client folder inside your application folder. If you want to debug them together, without a workspace you have to start two Visual Studio Code instances, one for server, one for client and you need to switch back and forth.
But right now (1.24) you can't add a single file to a workspace, only folders, which is a little bit inconvenient.