ActiveX is an extension to Microsoft's OLE and COM technologies used in applications and on the Internet. Using ActiveX, an Internet browser can interact with your computer more than what is available through HTML. For example, ActiveX allows users to scan their computer for viruses in their browser using free online antivirus scanners or scan their computer for any Windows updates.
Although there are benefits to using ActiveX, because it can interface outside the browser there are also various security threats and malware that can attack the computer using ActiveX. Therefore, unless you know what the ActiveX plug-in does and you trust the website that is asking to install the ActiveX plug-in we recommend not installing any ActiveX plug-ins.
Microsoft Internet Explorer is the only Internet browser that uses ActiveX, although many alternative browsers do have ActiveX plug-ins that can be installed. Browsers that do not support ActiveX use alternative plug-ins such as Flash, Java, and Shockwave.