Athens allows individuals to use single sign-on to access web resources, thus reducing the administrative burden for librarians and information managers. Springer continues to support customers who choose Athens access.
More Information regarding Athens: http://www.openathens.net/
Shibboleth is a standards based, open source software package for web single sign-on, allowing sites to make informed authorization decisions for individual access of protected online resources in a privacy-preserving manner. Springer currently supports access via the institution login located in the login area on the right side of the screen in the masthead.
More information regarding Shibboleth: http://www.internet2.edu/products-services/trust-identity-middleware/shibboleth/
See also: What is the difference between Athens and OpenAthens?