You can divide the browser's main display window into independent window frames, each simultaneously displaying a different document—something like a wall of monitors in a TV control room. Netscape invented the feature in the mid-1990s. Instantly popular, frames now are standard features for HTML 4 and XHTML.
Figure 11-1 is a simple example of a frame display. It shows how you can divide the document window into columns and rows of individual frames separated by rules and scroll bars. Although it is not immediately apparent in the example, each frame in the window contains an independent document. Frames may contain any valid content the browser is capable of displaying, including XHTML documents and multimedia. If the frame's contents include a hyperlink that the user selects, the new document's contents—even another frame document—may replace that same frame, another frame's content, or the entire browser window.
Frames are enabled with a special frame document. Its contents do not get displayed. Instead, the frame document contains tags that tell the browser how to divide its main display window into discrete frames and what documents go inside the frames.
The individual documents referenced and displayed in the frame
document window act independently, to a degree; the frame document
controls the entire window. You can, however, direct one frame's
document to load new content into another frame. You do that by
attaching a name to a frame and targeting the named frame with a special
attribute for the hyperlink <a>
tag.