Knowing when a user leaves a page

Hello all, I have a the following situation: - I have build up an marketplace-system wich needs to know, when a user enters or leaves a page of the system ( to build up a site-walk-track). This is no problem, if the user changes pages on the system (I can use the Environment-Variable HTTP_REFERER ans sessions to keep track of his site-walking) but i have a problem, when he leaves the site (by going to another site or terminate his connection). So my question is the following: Is it possible to get informations, when a page is no longer accessed by the user (javascript ?) ? cu Martin -- -------------- Martin Neimeier Tel:+49(6262)912344 Fax:+49(6262)912347