The Log Out button will terminate your session. Web sessions will terminated without you logging out even though your screen does not change. A session is considered active as long as you are interacting with the web server. For example if you do not click a submit button or change a screen within 20 minutes the session will time out and in effect log you off the system without changing your screen. You may think you are still connected properly but as soon as you push a button that will change the screen you will be asked to log in. When you are typing in a text field this is not an activity the web server uses to check your activity. Typing does not usually send a signal to the server.