Dynamic Data Exchange (DDE) is a form of interprocess communication on Windows that uses shared memory to exchange data between applications. Applications can use DDE for one-time data transfers and for ongoing exchanges and updating of data.
The DDE protocol is a set of messages and guidelines. It sends messages between applications that share data and uses shared memory to exchange data between applications. Applications can use the DDE protocol for one-time data transfers and for continuous exchanges in which applications send updates to one another as new data becomes available.
The preferred method for using DDE in your own application is with the Dynamic Data Exchange Management Library. DDEML provides an interface that simplifies the task of adding DDE capability to an application. Instead of sending, posting, and processing DDE messages directly, an application uses the functions provided by the DDEML to manage DDE conversations
MSDN article for DDE: http://msdn.microsoft.com/en-us/library/ms648711(v=VS.85).aspx
Wikipedia: http://en.wikipedia.org/wiki/Dynamic_Data_Exchange
