Many test engineers are have a doubt what is activex? what is the purpose of it? I going to explain in basic way here.
ActiveX controls are really small programs or snippets that will do some specific task. This ActiveX controls can be wriiten in C++, Delphi, Visual Basic, .Net and any language which supports COM components.
Actually ActiveX evolved from OLE concept of MicroSoft. Its purpose is, we can use the already written small program in any other applications to achieve the specific task like collecting data, Viewing some files, displaying animation kind of things, etc.
1. Microsoft Word application have a ActiveX component called SpellChecker. We are using that SpellChecker in Outlook and other applications also.
2. IE viewing the PDF files using ActiveX control designed by Adobe to view the PDF files.
3. Adobe Flash/Flex plug-Ins to view falsh videos etc.
ActiveX is only supported by IE and Windows. Also through ActiveX, you can control your whole machine and access your areas. This flexiblity turns as a drawback for users from malware attackers. Also this won't work in other browsers.
For this reason, another competitor borned as JavaApplets. Java Applets are small programs that can run from client side on browsers. This also requires a plug-in called Java Plug-In. But this will work in all browsers and environments. At the same time, this cannot provide full control over machine like ActiveX in windows.
Today we are using ADO(ActiveX Data Objects) for connecting DataBases and CDO(Collabaration Data Objects) to send mails etc. These are ActiveX componets.
Hope this discussion will give idea about ActiveX.