If you've been around the web for any length of time, you've probably heard of someone who has had their website copy or design (or both!) stolen. That is not OK. Although I'm a proponent of studying others to find out what works and what doesn't, copying others is a violation of copyright law and you can be penalized for it.
There is much confusion about copyright floating around too. If you're not sure how to interpret the law, talk to a lawyer. I know my attorney has come in handy when some thief has tried to steal my words without permission. And I'm getting ready to put him to work again because yet another uncreative website owner is not smart enough to write their own words.
But before you even begin, you need to pay a visit to the Copyright Basics page at the US Copyright Office online site. Here's a tiny excerpt that says a ton about copyright.
Copyright protection subsists from the time the work is created in fixed form. The copyright in the work of authorship immediately becomes the property of the author who created the work. Only the author or those deriving their rights through the author can rightfully claim copyright.