Inline Frames
To this point, our discussion has centered on frames that are
defined as part of a frameset. A frameset, in turn, replaces the
conventional <body> of a
document and supplies content to the user via its contained
frames.
The HTML 4 and XHTML standards let you do things a bit differently: you can also define a frame that exists within a conventional document, displayed as part of that document's text flow. These frames behave a lot like inline images, which is why they are known as inline frames.
All the popular browsers support inline frames.
The <iframe> Tag
Define an inline frame with the <iframe> tag. The <iframe> tag is
not used within a <frameset> tag. Instead, it appears
anywhere in your document that an <img> tag might appear. The <iframe> tag defines a rectangular
region within the document in which the browser displays a separate
document, including scroll bars and borders.
Use the src attribute with
<iframe> to specify the URL
of the document that occupies the inline frame. All of the other,
optional attributes for the <iframe> tag, including name, class, frameborder, id, longdesc, marginheight, marginwidth, name, scrolling, style, and title, behave exactly like the corresponding
attributes for the <frame> ...