A Shockwave plug-in is an extension to the Adobe Shockwave Player that allows a user to view interactive Web content. This may include in-browser games and other online entertainment, such as YouTube videos.
A plug-in itself acts as an add-on to Web browsers, such as Google Chrome or Mozilla Firefox. It gives that browser added functionality to allow the user to see images or videos that do not show up properly if the plug-in is not installed properly. Plug-ins for the Flash Player are becoming increasingly popular, as the Web becomes more commercialized, because they allow ads to display in Web pages.