All the databases mentioned above are public databases that provide their contents free of charge, and in many cases, they also provide a way to download data in bulk and integrate them into one’s own database. Therefore, it is very common that different database groups exchange their information with each other. This often raises some technical concerns. For example, as mentioned in Module 5, different databases may use different chemical representations to refer to the same molecule. This may result in incorrect chemical structure matching between the databases, leading to incorrect data integration. In addition, when one database has incorrect information, this error often propagates into other databases.