Oxford Single Sign-On
If you are a member of the University you should be issued with a University Card and a Single Sign-On (SSO) account.
The Oxford SSO account allows you to use the University (Nexus) email system, Weblearn (the University virtual learning environment), a variety of Library resources and online databases, and many other online tools and resources.
Once your University Card is issued, and you receive your registration paperwork, you will be able to activate and use your SSO account. 
The Oxford SSO account is administered by central University IT Services and, once used via your web browser, you should find that you do not need to enter your password again during the day to access other resources.
The username is in the format nuff9999
If you have forgotten your SSO password, please see http://help.it.ox.ac.uk/iam/registration/passwords