In certain earlier versions of Netscape and perhaps other Web browser , a helper application is a program that can be designated to handle a particular file type that the browser has received. The browser comes with the built-in ability to handle HTML files and Graphics Interchange Format and JPEG image files. For other files, the user must tell the browser the name of a helper application, a program that can view or otherwise process the special file. The user must also supply the program, usually by downloading it from the helper application's developer. The helper application runs as a separate application program in its own window.
A more popular alternative to a helper application is a plug-in , which runs in the browser's window so that streaming video and other processes can be an integral part of the Web page.