You mean like “Copyright © 2013 Sun-Times Media, LLC.” at the bottom of every page, and like this?
Copyright is automatic unless it’s placed in the public domain. And publishing something that is available to the public is not public domain.
Um. Yes. Exactly like that. :smack:
In the US, material is copyrighted at the moment of its creation regardless of whether you put a mark on it, and all that slapping a copyright notice on it manages to do is (IIRC) to make suing for material restitution easier to do.
The controversy about Cooks Source magazine 3 years ago is somewhat relevant (and I find quite amusing).
I’m still a little jealous that (as far as I know) none of my own threads have been stolen yet. 
Oh yay, they finally stole one of my threads. yay.