One of the great new features in iOS 11 and macOS High Sierra is shared documents. You can create almost any kind of file, and collaborate on it with other people. This can be a simple Pages document, or a complex song in GarageBand. In theory, the file will be updated with everybody’s changes, so you can work on the same project without emailing a zillion copies back and forth.
Currently, this feature ranges from a little shaky, to rock solid, depending on what apps you are using. Here’s how to share and collaborate using GarageBand in iOS 11.