Business Connectivity Services
Microsoft Business Connectivity Services (BCS) (formerly named the Business Data Catalog) provides read/write access to external data from line-of-business (LOB) systems, Web services, databases, and other external systems within Microsoft SharePoint 2010/2013 and Microsoft Office 2010/2013 applications. Both SharePoint 2010/2013 and Office 2010/2013 applications have product features that can use external data directly, both online and offline. Developers can gain access to a rich set of features and rapidly build solutions using familiar tools such as Microsoft Visual Studio 2010/2013 and Microsoft SharePoint Designer 2010/2013. MSDN.