Graphical Web browsers are client-side software applications that have been developed for the purpose of accessing files on the World Wide Web. By client-side is meant that through them the user sends instructions to a Web or other server requesting that particular files be downloaded on their computer. Browsers now also act as message centres. With many browsers you can read and send electronic mail, and read and post discussion group messages. Often they are referred to simply as Web browsers, or just browsers. They are graphical inasmuch as the interface includes various buttons, images, scroll bars and popup menus that are largely manipulated with the aid of a mouse.