Command Tab to show a 'hidden' app With Command W you 'hide' most of the apps excluding the ones with tabs.

But then when you do Command Tab, the hidden app doesn't show up.

How come?
How do you quickly bring back focus?
Command+W doesn’t hide the apps; it closes the current active window. That's why you can't show them up using Command+Tab, because the window is no longer exist.

You can hide application using Command+H. This shortcut won’t close the window, so you can bring all the hidden windows of a application back by using Command+Tab and selecting the application.