Activex control is a ready to use control.....
In our system there will be some inbuilt active x controls 
given by the os, such as...windows media player ,calender 
etc...thease controls can be used in any platform
(c ,c++,java,dotnet....).So we can also create the active x 
controls that can be used anywhere in any 
application...using actrive x controls in vc++ is very easy 
refer to an example by browsing in google .....if u need 
anything more mail me to diliprajug@yahoo.com