The settings in allow you to set up external applications that Opera can use to enhance your browsing experience.
Plug-ins are external applications that Opera can use to display images and video clips, show files, or play sounds that the browser is not able to handle by itself. Some of the most popular plug-ins are Adobe Flash Player, QuickTime, and Adobe Acrobat.
Plug-ins are separate applications, and therefore, Opera's various security settings will have no effect on how plug-ins work. For example, a plug-in such as RealPlayer can make use of cookies, and Opera's cookie settings will have no effect on these. Please keep in mind that any plug-in you add is an application installed on your computer. It is a good idea to do some research before installing new plug-ins and only download software from reputable sources.
To see a list of installed plug-ins, open the built-in plug-in overview. Note that Opera for Linux has a separate preference window for installing and locating plug-ins.
For more information, see the Plug-ins document online.
JavaScript, or more correctly, ECMAScript, is a means of embedding executable content in Web pages. It is used for everything, from making image links change when you hover over them with your mouse, to receiving and sending cookies.
These scripts are completely safe most of the time, but they may rarely be used for malicious purposes. JavaScript should not be able to access applications and information outside the Web page it resides on, but if you still fear JavaScript abuse, you can choose to disable it by selecting and unchecking "Enable JavaScript". Check this option again to enable JavaScript quickly, if you find sites that report errors, fail to display vital content, such as menus, or shut you out when you have JavaScript disabled.
You can also limit what Opera allows the script do, for example, whether to allow resizing or moving of windows. To change the default JavaScript settings, select , then selecting the JavaScript options button.