This paper presents a new way of designing navigation on the WEB. It describes the LYPO principle which consists in associating to an Internet site an applicative environment presented to the user as a kind of "virtual office" similar to the familiar user desktop metaphor, rather than a simple set of HTML documents. The appli -cative environment offers more freedom of action to the site visitor, and allows the webmaster to design a richer site in terms of fonctionnality and interaction.