The new name for programmable elements formerly known as OLE controls, OCXs, or OLE custom controls. Controls previously built with the MFC Control Developer's Kit meet the ActiveX control specification.
An ActiveX control, like a built-in control, is an object that you place on a form to enable or enhance a user's interaction with an application. ActiveX controls have events and can be incorporated into other controls. These controls have an .ocx file name extension.