A community of magically gifted individuals seeking to document, study, and possibly contain, magical artifacts and entities that might pose issues or benefits to the people of Tamriel.
It began simply as a studious endeavor to understand magic and magical items & entities more clearly but evolved as some dangerous items and entities were discovered. Quickly, it became more than just a study group and spread throughout Tamriel as a means to learn about, understand, and safeguard the populace from Daedric or any other magical things that exist out in the world.
Their mantra; Study, Contain, Protect, became a declaration that marked their halls and pamphlets that they handed out to the populace at large. All magical objects or entities that they managed to capture and isolate from the populace became documented in their writings with the initials of their mantra and organization, and a number listed after it. Likewise, said objects and entities became referred to as SCPs.