Overview
Shibboleth (an open-source implementation of SAML) is a framework that allows applications to authorize access via an organization's Identity Provider Service. Shibboleth can be used to allow access to your application from any organization on the Internet that supports SAML. Conversely, it can also be used to allow UIC users access to third party applications using their UIC credentials.
Applications hosted by UIC can register with the I-Trust Federation for free:
https://itrust.illinois.edu
Applications not hosted by UIC must register with the InCommon Federation:
https://incommon.org
For more information regarding the yearly InCommon Federation fee structure see https://incommon.org/join-incommon/fees
Discovery Service
A discovery service is a web page that asks you to select your institution, after which you are redirected to that institution's authentication service via SAML. For instance, the discovery service for uofi.box.com (hosted by illinois.edu) asks you to select one of UIUC, UIC, or UIS. If you misclick and select the wrong organization you can reset your selection for the illinois.edu discovery service by going to this link:
https://discovery.illinois.edu/discovery/DS
For more information on SAML, see:
https://en.wikipedia.org/wiki/Security_Assertion_Markup_Language