ActiveX control

The basic building block of Microsoft's ActiveX specification. An ActiveX control is a software module that cannot run by itself, but requires an ActiveX container such as a Web browser, a word processor, or a spreadsheet. Each control delivers a specific function such as database access, user-interface elements, or file access and can communicate with another ActiveX control, an ActiveX container, or the underlying Windows operating system.

Unlike Java applets, which for security reasons run in a sandbox designed to protect the file system from unauthorized access, ActiveX can directly access files. To provide a measure of security, ActiveX controls are packaged with digital certificates that prove the origin of the control.