This lecture is a brief introduction into the SAML based SSO system at the University of Debrecen. It shows the origins, its history, the applications built upon it, the mechanisms working in the background. In addition to these, in the focus of the lecture are some e-learning related applications, such as local Moodle learning environments of various departments and faculties, e-portfolio systems, and services of the library (e.g. DSPACE). Naturally there is SAML in the background of all of these applications.