If you use Microsoft® Visual Basic® to implement your component, you will create an ActiveX™ DLL file. An ActiveX DLL is a COM component that exposes its methods to clients through Automation. The Visual Basic 5.0 New Project window provides a tool to assist you in creating the basic framework for an ActiveX DLL.
ActiveX components use Automation to present an easy way of creating object instances. Components that use Automation are known as Automation servers. Clients of Automation servers are known as Automation controllers. When an ASP script creates an instance of an object from your component, it is acting as an Automation controller.
For more information on Automation, see Automation in the COM and ActiveX Object Services book of the Platform SDK.