External Content Types

SharePoint 2010 adds the notion of external content types. The content type, first introduced in SharePoint 2007, is a way of describing an entity of information stored in SharePoint. Document content types can be items such as contracts, policies, and forms. Nondocument content types can be items such as announcements, tasks, or contacts. All these are content types whose information is physically stored within the SharePoint taxonomy. Each would have its respective set of attributes, known as columns, properties, or metadata.

An external content type is just what it sounds like: an entity whose underlying data exists external to SharePoint. Just like a SharePoint content type, an external content type will also have its set of attributes or columns. Using BCS, external content types can be defined and made available for consumption within SharePoint.