Microsoft ActiveX Controls Overview

Microsoft® ActiveX® controls, formerly known as OLE controls or OCX controls, are components (or objects) you can insert into a Web page or other application to reuse packaged functionality someone else programmed. For example, the ActiveX controls that are included with Microsoft Internet Explorer version 3.0 or higher allow you to enhance your Web pages with sophisticated formatting features and animation.

A key advantage of ActiveX controls over Java applets and Netscape plug-ins is that ActiveX controls can also be used in applications written in many programming languages, including all of the Microsoft programming and database languages.

There are literally hundreds of ActiveX controls available today with functionality ranging from a timer control (which simply notifies its container at a particular time) to full-featured spreadsheets and word processors. If you can imagine it, you can do it with an ActiveX control.

You can add ActiveX controls to your Web pages by using the standard HTML <object> tag. The <object> tag includes a set of parameters that you use to specify which data the control should use and to control the appearance and behavior of the control.

Microsoft Internet Explorer (version 3.0 or higher) comes with a set of ActiveX controls that it uses. With some of these controls, you can:

• Simplify and automate your authoring tasks (for example, display "NEW!" images for new items on your site with a date specification; after that date, the images will automatically become invisible).
• Display data in ways other than text and tables (for example, charts or text displayed at different angles).
• Add functionality to your pages (for example, timers, animation, and background downloading).

The ActiveX controls that are provided with Internet Explorer are installed automatically when the user installs Internet Explorer 3.0 or higher. Once installed, ActiveX controls run automatically when a Web page containing them is displayed -- users do not need to download any additional files.

If you're a Web author, you can take advantage of the ready-to-use ActiveX controls written by some third-party companies. These controls can be found on many places. If you're a programmer, you can write your own controls using Visual C++® and one of the ActiveX control frameworks: the Microsoft Foundation Class Library (MFC), the ActiveX Template Library (ATL), or the BaseCtl framework.