COM components are the key to building powerful, real-world Web applications. Components provide functionality that you use in your scripts to perform specialized tasks, such as executing financial transactions or validating data. ASP also provides a set of base components that you can use to greatly enhance your scripts.
About Components

A COM component is a reusable, programmatic building block that contains code for performing a task or set of tasks. Components can be combined with other components (even across networks) to create a Web application. COM components execute common tasks so that you do not have to create your own code to perform these tasks. For example, you can use a stock ticker component to display the latest stock quotes on a Web page. However, it would be difficult to create a script that provides the same functionality. Also, the script would not be as reusable as a component.