The simplest methods are time oriented in which one method based on total session time and the other based on single page stay time. The set of pages visited by a specific user at a specific user at a specific time is called page viewing time. It varies from 25.5 minutes to 24 hours while 30 minutes is the default timeout. The second method depends on page stay time which is calculated with the difference between two timestamps. If it exceeds 10 minutes the second entry is assumed as a new session. Time based methods are not reliable because users may involve in some other activities after opening the web page and factors such as busy communication line, loading time of components in web page, content size of web pages are not considered.