Single source of truth (SSOT) refers to the practice of structuring information models and associated data schema such that every data element is stored exactly once.   Linkages to this data element are by reference only because all other locations of the data just reference back to the primary “source of truth” location. Any updates to the data element in the primary location propagate to the entire system without the possibility of a duplicate value somewhere being forgotten.   Read more about SSOT here.