Browsers are the key client applications of the internet.
A web site acts as a server, serving files to the client browser for viewing. The browser takes the information and renders it appropriately depending on whether it is HTML, image, or multimedia. Plug-ins are extra software embedded into the browser that allow functionality outside the standard viewing of HTML pages, such as multimedia. There are also applications known as helper applications. Helper applications run independently of the browser, so closing the browser does not affect the helper application.