Each time I gave a new version of my project to our tester then he placed the new project within a new root folder ( a new site then ). Inside the php files there are session variables which are created and used. So the problem comes when he opens two sites at the same time to compare the two releases : with the first site he opens a page , then a session variable is created. Now he opens the second site and go to a particular page then he is directly redirected to a particular page because of the session variable from the previous site. So how to create site-independent session variables ?