Laying Out Frames: Frames

Dividing a single browser window into multiple regions for separate document viewing is called framing. Netscape Communications, maker of the popular web browser Netscape Navigator, has proposed extensions to HTML to facilitate framing. To promote these extensions, they have also implemented them into their latest editions of the Netscape Navigator. The Microsoft Corporation, engaged in fierce competition with Netscape to become the world's guide to the Internet, has also implemented Netscape's frame extensions (along with a few more of their own) into their latest web browser, the Internet Explorer.

Due to the wide acceptance of these frame extensions, the filename extensions .html and .htm have been expanded to signify not only one, but two kinds of documents: frameset documents and body documents.

frameset documents

Obviously, a frames-capable browser cannot display documents in frames until it knows about the browser window's frame layout. Frameset documents (formerly called "layout documents" in an earlier edition of this tutorial) contain the information necessary for the browser to determine what kind of frame structure it should use when dividing the window into frames.

body documents

Although frameset documents contain information about the web document's frame layout, they do not contain any information about the actual contents of the frames (i.e., the documents displayed within the frames). Rather, each frame declaration in the frameset document contains a URL referencing a document that the browser should display within the frame. Documents containing content, rather than frame layout information, are called body documents, for a reason which will be apparent later. All normal, non-framed documents, including the document which you are reading right now, belong to this category of web documents. Before the introduction of frames, and hence the frameset documents, all documents were body documents.