SCPs are anomalies that defy the laws of physics and reality, or something that is unable to explain, and are captured and contained by the SCP Foundation, whose goal is to contain all of these anomalies to protect society and hide the SCPs, even if the anomaly is harmless. There are many MTF units who specialize in securing and containing SCPs, researchers who study and test on the contained SCPs to further understand the SCPs, and D-Class are disposable criminals used for the SCP testings.