Question about IFrame

I had been going through Iframe related questions and got stuck with this.

They break the one-document-per-URL paradigm, which is essential for the proper functioning of the web (think bookmarks, deep-links, search engines, ...).

Moreover, if I ask开发者_开发问答 you to tell me the difference between Iframes and Frames, what is the easiest way to explain it?

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Frame allows you to display multiple documents on page.

They all have distinct URLs which are hidden from you. So, you cannot bookmark them separately.

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An iframe is a frame in an otherwise normal document.

Normal frames are placed in a document which consists entirely of frames (plus, hopefully, some fallback content from user agents that don't support them).