Interfaces used to make web part connections.
ICellProvider: This API is now obsolete. Enables a Web Part to communicate with a Web Part that implements the ICellConsumer interface to work with a single value item.
IWebPartField : Defines a provider interface for connecting two server controls using a single field of data.
IRowProvider: This API is now obsolete. Enables a Web Part to send a row of data to a Web Part that implements the IRowConsumer, ICellConsumer, IFilterConsumer, or IParametersInConsumer interface.
IWebPartRow: Defines a provider interface for connecting two server controls using a single field of data.
IListProvider: This API is now obsolete. Defines events that a Web Part can implement so that it can provide an entire list (rowset) of data to another Web Part that implements the IListConsumer interface.
IWebPartTable: Defines a provider interface for connecting two server controls using an entire table of data.
IFilterProvider: This API is now obsolete. Used to communicate with a Web Part that implements IFilterConsumer interface to provide filter information to the consumer.
IWebPartParameters: Defines the contract a Web Parts control implements to pass a parameter value in a Web Parts connection.
Source: http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.webparts.aspx
