Shadow-banning is when you're banned from the entire site. It can't be done for a single community, as far as I know. There IS a catch to a shadow-ban, though: You can view everything on Reddit. You can log in just fine and everything would seem normal. However, no one can see any posts or comments you've made after being shadow-banned. In addition, you're not notified about being shadow-banned, and if you view your own profile while logged in then everything displays just fine.  Basically, It's the type of ban where you would never know you were banned unless someone told you or you randomly decided to view your own profile while logged out. I think it's to cause less "I was banned so I just made a new account and I'm continuing to do the thing that got me banned in the first place" situations.