Kinda like how you could physically cut out a picture of a person in a mag with scissors so it's just the person with no background at all.

Or you could just erase the background rather than cut the subject out.

I dunno about the shit like that, but here's an example.

Here's an example:
http://graphicssoft.about.com/od/photoshop/l/blrbps_1jet.htm
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So you do yourself an injustice to judge me by yesterday, when I have moved on.