Most web pages are variations of these three layouts. This page itself is an example of a 'BOTTOM INDEX' layout.

Layout selection is often made based on the type of information to be presented. For example, the 'TOP INDEX' layout lends itself to presenting a large number of links to other sites. If the content of the page deals mostly with a single topic a 'BOTTOM INDEX' layout prevents things such as links to related documents or a main index from being a distraction. Wider screen resolutions have helped make the 'LEFT INDEX' layout very popular as it provides ease of navigation without cluttering the page's main presentation.