Okay, what if I were to post an article on my site, and it was from another site, but, what if I quote a portion or the whole article right in my article and adding a side of my own opinion or annalysis? Is this a good idea or is it still stealing content? I of course would source the material, so I'll be okay by doing that, but is there any other legal troubles I could face for quoting a portion of an article or the whole thing?