ActiveX refers to the Microsoft’s ActiveX controls or functions. These are components that may be used in building programs and applications which may be accessed through regular web browsers. Microsoft released this in 1996.

Today, many Windows applications utilize ActiveX controls. One of these is Internet Explorer. Being an example of an ActiveX control, IE can also facilitate the embedding of such controls in other websites or pages.

Other controls could come in the form of dialog boxes or command buttons. Since ActiveX controls are also present in Microsoft Word, some tools that are available in Word may also be made available in other programs running on ActiveX controls.

Active X is considered the Microsoft counterpart to Java applets. Both of these are downloadable and executable and run on the computer instead of on the server. However, ActiveX controls are only designed for use on Microsoft’s system. This includes Internet Explorer, as well. On the other hand, Java applets may be used on most systems or platforms.

In order to make writing of controls much simpler, Microsoft has produced wizards and other tools. Also, if an ActiveX control is needed to perform a certain function, it is almost automatically downloaded and installed. This automatic download feature has raised some security concerns. Nowadays, it is quite common for some form of user validation to be required before a control is installed.

Care must be exercised in the use of ActiveX controls. These can facilitate the installation or spread of certain viruses from malicious sites. Spyware can also be accidentally downloaded this way.