There are many acronyms and definitions in the world of the API so we have put together a short list containing the most used terms...
Central Authentication Service (CAS) is a single sign-on protocol for the web. Its purpose is to permit customers to access multiple applications while providing their credentials (such as user ID and password) only once. It also allows web applications to authenticate customers without gaining access to their security credentials, such as a password.
Command Line Interface to HTTP. Extremely popular for testing APIs and the building block for many client libraries.