Dual Monitor Advantage

Okay, I'm a noob about this "dual monitor" thing, can anyone tell me the main advantage of it?

I'm thinking that, is it possible to use one monitor to watch anime (full screen) while I use the other monitor to surf net, chat, watever, etc.? 

Goddammit you people are retarded.

OS comes from Microsoft.
Video drivers and associated software comes from nVidia/ATI.

Third party.

What the fuck is so hard to understand?

And Krita >>>>>>> GIMP now.  Last I checked, GIMP doesn't even support CYMK.