Forum Moderators: phranque
If you are talking about the HTML markup, then there is no way to "protect" it whatsoever (despite claims to the contrary by some firms offering "secured" or "encoded" markup). That's just how the web works - the HTML is sent as text, and the browser uses it to render the page. Same goes for cascading stylesheets and, to a certain extent, Javascript (which can be obfuscated, which can hinder decipherment, but that's all).
In the case of images, much the same is true - the image files have to be downloaded to the client to be rendered, and they are cached by the browser.
In reality, there is little to protect - the HTML can be copied, sure, but the design would be usually trivial to recreate even without the original source. The images are low-quality for web work, so even if they can be copied, they have very little use outside the web sphere. You can prevent "hotlinking" (inserting images stored on your site directly into a remote page), however.
The real value of a site lies in any server-side scripting, such as in your content-management system, as well as your databases - and that is already well-protected from copying by the end user.