BCS External Lists

External Lists are completely new to SharePoint 2010 and Business Connectivity Services.

With an External List you can pick an External Content Type and the list will display the data from your BCS entity within SharePoint. To users it looks like the data displayed is in a normal SharePoint list but it is actually being pulled live from your data source. As soon as your Line of Business systems data updates, people viewing the list will see the new data.

Although the data looks like it is standard contained within a standard SharePoint list, it does still remain within your Line of Business system. This means some functionality such as alerts and workflows are not possible on External Lists as the list will only update when someone views the actual page the list is placed on - not in the background which is what would be needed for alerts and workflows to fire.