What is ActiveX control, how ActiveX control works?

ActiveX controls are small programs, sometimes also called "add-ons," that are used on the Internet. ActiveX is not a programming language, but rather a set of rules for how applications should share information. They can enhance your browsing experience by allowing animation or they can help with tasks such as installing security updates at Microsoft Update. Some Web sites require you to install ActiveX controls to see the site or perform certain tasks on it. When you visit such a site, Internet Explorer asks if you want to install the ActiveX control. An ActiveX control can be automatically downloaded and executed by a Web browser if your Internet Explorer setting is not set properly.

Unfortunately, ActiveX controls are like any other software program which can be misused. They can stop your computer from functioning correctly, collect your browsing habits and personal information without your knowledge, or can give you content, like pop-up ads that you don't want. Also, " good " ActiveX controls might contain unintended code that allows "bad" Web sites to use them for malicious purposes.

An ActiveX control is similar to a Java applet. Unlike Java applets, however, ActiveX controls have full access to the Windows operating system. This gives them much more power than Java applets, but with this power comes a certain risk that the applet may damage software or data on your machine.

Programmers can grant to ActiveX controls a much higher level of control over Windows than Java applets ever achieve, making them more powerful but also potentially more dangerous.

Malware, such as computer viruses and spyware, can be accidentally installed from malicious websites using ActiveX controls (drive-by downloads).