Object Linking and Embedding

Object Linking and Embedding (OLE) is a technology that allows embedding and linking to documents and other objects developed by Microsoft. It is found on the Component Object Model. For developers, it brought OLE custom controls (OCX), a way to develop and use custom user interface elements. On a technical level, an OLE object is any object that implements the IOleObject interface, possibly along with a wide range of other interfaces, depending on the object's needs.

Reference:
http://en.wikipedia.org/wiki/Object_Linking_and_Embedding