DEFINITION of ActiveX
BREAKING DOWN ActiveX
ActiveX is used to create pieces of pre-coded software called ActiveX controls (similar to plug-ins or add-ins on other browsers). If, for example, you are trying to access a webpage that has plays Flash files, you can download a Flash ActiveX control in order to play the files directly in your browser without opening a new application. Basically, the controls extend a browser's functionality, allowing it to perform tasks it would otherwise not be capable of doing natively. It's particularly useful for playing videos and other multimedia content, skipping the step of opening a seprate media player.
Partly because malicious use of ActiveX controls became such a widespread problem, ActiveX controls are far less common today. Many browsers either disable ActiveX controls by default or do not support them at all. Google Chrome, for example, won't do so automatically, though support can be added via a browser extension. Interestingly, even Microsoft itself seems to be dialing back on its software: its new Edge, the browser that is replacing its Internet Explorer on Windows operating systems, does not support ActiveX.