A few things there Leon. One, guests obviously don't show up on the list of users. Two, users can choose to be invisible and they still show up as members in the count but don't show up on the user list. Three, people only show up at the top of a forum if they have gotten to the forum thread list in the last minute or so. Many people browse the forum by using the new threads option so they never show up on those lists. The software counts people as logged in until they haven't had activity for a set period of time. The reason for that is for the exact reason you state - many people don't log off. Even if they don't log off if they don't have any activity for a set period of time then they are no longer counted. That's why we tried that experiment. I went to some competing sites and by having someone else log in as me and then log off the internet I watched to see how long I was still shown as being online on that site. Then I changed our setting to that to compare.