What is Oracle Single Sign On (SSO) Server? and What are its benefits?

Oracle Application Server Single Sign-on enables you to use single user name and password and optionally realm name to log in to all features of Oracle AS as well as web applications available in OC4J.Oracle AS SSO provides the following benefits, 

1. Reduced Administration costs - SSO server eliminates the need to use multiple accounts and passwords
   
2. Convenient - User doesn't need to maintain separate user name and passwords of different applications
   
3.  Increased Security