Your Oxford username and Single Sign-On password can be used to log in and this will start a Single Sign-On session. Single Sign-On means that after your initial login, you can use associated services without having to re-enter your username and password.
Oxford Single Sign-On is the only login page where you should enter your Oxford username and Single Sign-On password. You can think of the Single Sign-On as a central authentication system that is trusted by various services in Oxford to handle all the username and password checking so that each individual service doesn't need to do it for itself. Once you have entered your Single Sign-On details you will need to enter your additional authentication credentials to proceed. See Multi-factor authentication.
To end your Single Sign-On session ("logout") you will need to close your web browser (that includes quitting all running copies of your web browser).