What is BDCs?

BDCs typically refers to Business Data Connectivity Services (or Business Data Catalog in older SharePoint versions). BDCs provide a way to integrate data from external systems (such as databases, web services, or custom applications) into SharePoint environments. Users can then interact with this external data as if it were native SharePoint data, enabling scenarios like displaying data in lists, searching across external systems, and performing actions on external data directly from SharePoint. The core purpose is to bridge the gap between SharePoint and external data sources to create a more integrated user experience.