There are several ways to make use of your business data within SharePoint sites. You can create business data columns for your SharePoint lists so that you have a pull-down selection of your business data in your list. Additionally, you can use the business data Web Parts SharePoint provides to display and connect business data within the context of your site.
MOSS 2007 provides a new column type for your lists so that you can associate business data with the content stored in lists and libraries. There are several reasons for doing this:
Centrally stored information: If you want to be able to reuse the customer list from your CRM tool throughout your organization, it should be added to your BDC.
Consistent use of data and fields: By reusing a business data field, you can consistently refer to the same customer list every time you tag a document or list item. This consistent use should make finding all SharePoint related items for that customer easier.
Exposing business data actions: BDC columns added to a list will also expose the associated action for that business data, enabling users to execute the actions.
When you add a BDC column, you can select other attributes of the BDC entity that you would like to show along with the primary value for the Business Data. For example, if your BDC contains a customer list, you may want to add Contact as a business data column, but also show the e-mail address ...