In addition to the built-in controls that appear in the toolbox, Microsoft Access supports ActiveX controls (formerly known as custom or OLE controls). 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 usually have an .dll or .ocx file name extension. The Calendar control is an example of an ActiveX control.